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incompatible building materials
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Incompatible Building Materials
A report documenting premature failure in residential
construction resulting from material incompatibility
Canada Mortgage and Housing Corporation
June 2003
Prepared by:
J.F. Burrows Consulting
For:
Policy and Research Division,
Canada Mortgage and Housing Corporation
CMHC offers a wide range of housing-related information, For details, call 1 800 668-2642
or visit our Web site at www.cmhc.ca
Cette publication est aussi disponible en français sous le titre : Matériaux de construction incompatibles
Rapport sur la défaillance prématurée de bâtiments résidentiels découlant de l’incompatibilité de matériaux
de construction, 63264
This research project was (partially) funded by Canada Mortgage and Housing Corporation (CMHC). The contents,
views and editorial quality of this report are the responsibility of the author(s) and CMHC accepts no responsibility for
them or any consequences arising from the reader's use of the information, materials and techniques described herein.
National Library of Canada cataloguing in publication data
Main entry under title:
Incompatible building materials: a report documenting premature
failure in residential construction resulting from material incompatibility
Issued also in French under title: Matériaux de construction incompatibles.
ISBN 0-662-34596-7
Cat. no. NH15-411/2003E
1.
2.
3.
I.
Building failures.
Building materials.
Buildings – Specifications.
Canada Mortgage and Housing Corporation.
TH441.I52 2003
691
C2003-980237-X
© 2003 Canada Mortgage and Housing Corporation.
All rights reserved. No portion of this book may be reproduced, stored in a retrieval system or transmitted in any form
or by any means, mechanical, electronic, photocopying, recording or otherwise without the prior written permission of
Canada Mortgage and Housing Corporation. Without limiting the generality of the foregoing no portion of this book
may be translated from English into any other language without the prior written permission of Canada Mortgage and
Housing Corporation.
Printed in Canada
Produced by CMHC
Note to users
This report documents and shares information about building material incompatibilities.
It opens with a “Quick Reference Guide to Incompatibilities.” The Quick Reference Guide is a fast
and easy way to find out if a material is incompatible with other materials.
Appendix B, page 48, is the survey form that was CMHC used to solicit incompatibility reports for
this document. We encourage you to share your experience with additional incompatible building
materials by completing the survey and returning it to CMHC.
The text of this document is also available on-line, at the CMHC Web site, at www.cmhc.ca.
i
Table of Contents
Quick reference guide to incompatibilities.....................................................1
Executive Summary ........................................................................................5
Introduction ...................................................................................................7
Purpose.....................................................................................................................................7
Criteria for inclusion ................................................................................................................7
Research intent and accuracy ....................................................................................................7
Causes of material incompatibility............................................................................................8
Methodology ............................................................................................................................9
Advisory committee............................................................................................................9
Research..............................................................................................................................9
Survey...............................................................................................................................10
Screening ..........................................................................................................................10
Verification .......................................................................................................................10
Report ..............................................................................................................................10
Communication plan..............................................................................................................11
Trend analysis .........................................................................................................................11
Examples of Incompatibility .........................................................................13
Division 1–General Requirements....................................................................................13
Division 2–Sitework .........................................................................................................13
Division 3–Concrete.........................................................................................................14
General information .........................................................................................................14
3.1.1 Concrete/Steel (ferrous metal) .................................................................................14
3.1.2 Concrete/non ferous metals .....................................................................................14
Division 4–Masonry .........................................................................................................15
Division 5–Metals.............................................................................................................16
General information .........................................................................................................16
Types of protection ...........................................................................................................18
Other metal-related reports.....................................................................................................19
5.1.1 Copper tubing/Aggressive soils ................................................................................19
5.1.2 Copper pipe/Plumbing ............................................................................................20
5.1.3 Copper flashing/Metal fasteners...............................................................................20
5.1.4 Metal strapping seismic restraint/Hot water heaters.................................................21
Division 6–Wood and Plastics..........................................................................................22
Other wood - related reports ............................................................................................22
6.1.1 Metal Fasteners/Cedar, redwood and treated wood products in exposed locations...22
Division 7–Thermal moisture protection .........................................................................23
General information .........................................................................................................23
7.1 Envelope...........................................................................................................................23
7.1.1 Housewrap/Surfactants ............................................................................................23
7.1.2 Exterior membranes/Sunlight ..................................................................................23
7.1.3 Peel-and-stick membranes/Vinyl windows ...............................................................24
Incompatible Building Materials
7.1.4 Vinyl siding/Rigid insulation ...................................................................................24
7.2 Roofing.............................................................................................................................24
7.2.1 Bituminous membranes/Polyisocyanurate foam insulation ......................................24
7.2.2 Bitumens/Polystyrene foam insulation .....................................................................26
7.2.3 EPDM membranes/Bituminous-based air barrier membranes and flashings ............26
7.2.4 Roofing membranes/Heat-applied roofing products ................................................26
7.3 Sealants.......................................................................................................................26
General information .........................................................................................................26
7.3.1 Sealants/Rigid insulation .........................................................................................28
7.3.2 Sealants/Vent pipes ..................................................................................................29
7.3.3 Silicone sealants, acid-cure/Other materials .............................................................30
7.3.4 Silicone sealant/Mirrors ...........................................................................................30
7.3.5 Silicone sealants/General..........................................................................................30
7.3.6 Plumbers putty/Sunlight..........................................................................................31
7.3.7 Polyurethane sealant/Polyethylene ...........................................................................31
7.3.8 Polyurethane sealant/Asphaltic materials..................................................................32
Division 8–Doors and windows .......................................................................................33
Division 9–Finishes ..........................................................................................................34
9.1 Coatings ...........................................................................................................................34
General information .........................................................................................................34
9.1.1 Paint/Wood knots....................................................................................................35
9.2 Flooring, resilient..............................................................................................................36
General information: ........................................................................................................36
9.2.1 Resilient flooring/Concrete sub-base........................................................................36
9.2.2 Resilient flooring/Wood panel sub-floor ..................................................................36
9.2.3 Resilient flooring/Floor fills and toppings................................................................37
9.2.4 Resilient flooring/Latex-backed rugs and mats.........................................................37
Division 10–Specialties.....................................................................................................38
Division 11–Equipment ...................................................................................................38
Division 12–Furnishings ..................................................................................................38
Division 13–Special construction .....................................................................................38
Division 14–Conveying systems .......................................................................................38
Division 15–Mechanical ...................................................................................................39
15.1 High-temperature vent pipes/Combustion gas..........................................................39
Division 16–Electrical ......................................................................................................40
16.1.1 Smoke alarms/Halogen lighting.............................................................................40
16.1.2 Electrical wiring/CPVC pipe .................................................................................40
Trend Analysis ...............................................................................................41
Education ...............................................................................................................................41
Sealants...................................................................................................................................41
Builder awareness....................................................................................................................41
Uses of materials .....................................................................................................................42
Incompatible Building Materials
Instruction labels ....................................................................................................................43
Trend summary ......................................................................................................................43
Building Code Issues .....................................................................................44
Appendix A: Research Sources .......................................................................45
Industry associations...............................................................................................................45
Architectural associations ........................................................................................................45
Government and regulatory bodies .........................................................................................46
Research and university ..........................................................................................................46
Publications ............................................................................................................................46
Periodicals...............................................................................................................................47
Appendix B: Survey .......................................................................................48
Acknowledgements .......................................................................................49
Advisory committee................................................................................................................49
Technical reviewers .................................................................................................................49
Survey respondents .................................................................................................................49
Quick reference guide to incompatibilities
This Quick Reference Guide lists materials that may be incompatible when used with another
material or materials. The materials are arranged in alphabetical order and the reference code directs
the reader to the Division with details about the incompatibility.
Using the Quick Reference Guide
Name of
material
Division Number
and name of
incompatible
material
Page
number
Polyurethane
7.3.7 Polyurethane sealant/Polyethylene–31
When you want to find if a material is incompatible with other materials, find the name of the
material in the bold names in the following alphabetical list.
The line or lines under the name gives, first, the Division Number and report number, then the
materials that are incompatible and then the page number where you will find complete
information.
1
Incompatible Building Materials
Air barrier
7.2.3 EPDM
membranes/Bituminousbased air barrier
membranes and
flashings–26
Alarms, smoke
16.1.1 Smoke alarms/Halogen
lighting–40
Asphaltic materials
7.3.8 Polyurethane
sealant/Asphaltic
materials–32
Bitumens
7.2.2 Bitumens/Polystyrene
foam insulation–26
7.2.3 EPDM
membranes/Bituminousbased air barrier
membranes and
flashings–26
Bituminous membranes
7.2.1 Bituminous
membranes/Polyisocyanurate
foam insulation–24
7.2.2 Bitumens/Polystyrene
foam insulation–26
Concrete
General Information–14
3.1.1 Concrete/Steel (ferrous
metal)–14
3.1.2 Concrete/Non-ferrous
metals–14
9.2.1 Resilient
flooring/Concrete subbase–36
Coatings
General Information–34
9.1.1 Paint/Wood knots–35
2
Combustion
15.1.1 High-temperature vent
pipes/Combustion–39
Floor fills and toppings
9.2.3 Resilient flooring/Floor
fills and toppings–37
Copper flashing
5.1.3 Copper
flashing/Metal fasteners–20
Flooring, resilient
General Information–36
9.2.1 Resilient
Copper pipe
flooring/Concrete sub5.1.1 Copper tubing/Aggressive
base–36
soils–19
9.2.2 Resilient flooring/Wood
panel sub-floor–36
5.1.2 Copper
9.2.3 Resilient flooring/Floor
pipe/Plumbing–20
fills and toppings–37
CPVC pipe
16.1.2 Electrical wiring/CPVC 9.2.4 Resilient flooring/Latexbacked rugs and mats–37
pipe–40
Foam insulation
Electrical
16.1.1 Smoke alarms/Halogen 7.2.1 Bituminous
lighting–40
membranes/Polyisocyanurate
16.1.2 Electrical wiring/CPVC
foam insulation–24
pipe–40
7.2.2 Bitumens/Polystyrene
foam insulation–26
EPDM membranes
7.2.3 EPDM
Halogen lighting
membranes/Bituminous16.1 Smoke alarms/Halogen
based air barrier
lighting–40
membranes and
Hot water heaters
flashings–26
5.1.4 Metal strapping seismic
Exterior membranes
restraint/Hot water
7.1.2 Exterior
heaters–21
membranes/Sunlight–23
7.1.3 Peel-and-stick
membranes/Vinyl
windows–24
Fasteners
5.1.3 Copper
flashing/Metal fasteners–20
6.1.1 Metal fasteners/Cedar,
redwood and treated wood
products in exposed
locations–22
Flashing, copper
5.1.3 Copper
flashing/Metal fasteners–20
Heat
7.2.4 Roofing
membranes/Heat-applied
roofing products–26
15.1 High-temperature vent
pipes/Combustion–39
Housewrap
7.1.1 Housewrap/
Surfactants–23
Insulation, rigid
7.1.4 Vinyl siding/Rigid
insulation–24
Incompatible Building Materials
7.2.1 Bituminous
membranes/Polyisocyanurate
foam insulation–24
7.3.1 Sealants/Rigid
insulation–28
Latex-backed rugs and mats
9.2.4 Resilient flooring/Latexbacked rugs and mats–37
Lighting
16.1.1 Smoke alarms/Halogen
lighting–40
Mechanical
7.3.2 Sealants/Vent pipes–29
15.1.1 High-temperature vent
pipes/Combustion gas–39
Metals
General Information–16
3.1.1 Concrete/Steel (ferrous
metal)–14
3.1.2 Concrete/non-ferrous
metals–14
5.1.1 Copper tubing/Aggressive
soils–19
5.1.2 Copper pipe/
Plumbing–20
5.1.3 Copper flashing/ Metal
fasteners–20
5.1.4 Metal strapping seismic
restraint/Hot water
heaters–21
Mirrors
7.3.4 Silicone
sealant/Mirrors–30
Membranes, bitimunous
7.2.1 Bituminous
membranes/Polyisocyanurate Nails
foam insulation–24
6.1.1 Metal fasteners/Cedar,
redwood and treated wood
Membranes, EPDM
products in exposed
7.2.3 EPDM
locations–22
membranes/BituminousPaint
based air barrier
membranes and
General Information–34
flashings–26
9.1.1 Paint/Wood knots–35
Membranes, exterior
7.1.2 Exterior
membranes/sunlight–23
7.1.3 Peel-and-stick
membranes/Vinyl
windows–24
Membranes, peel-and-stick
7.1.3 Peel-and-stick
membranes/Vinyl
windows–24
Membranes, roofing
7.2.4 Roofing
membranes/Heat-applied
roofing products–26
Peel-and-stick membranes
7.1.3 Peel-and-stick
membranes/Vinyl
windows–24
Pipe, CPVC
16.1.2 Electrical wiring/CPVC
pipe–40
Plumbing
5.1.2 Copper pipe/
Plumbing–20
Polyethylene
7.3.7 Polyurethane
sealant/Polyethylene–31
7.3.8 Polyurethane
sealant/Polyethylene–32
Polyisocyanurate foam
insulation
7.2.1 Bituminous
membranes/Polyisocyanurate
foam insulation–24
Polystyrene foam insulation
7.2.2 Bitumens/Polystyrene
foam insulation–26
Polyurethane
7.3.7 Polyurethane
sealant/Polyethylene–31
7.3.8 Polyurethane
sealant/Asphaltic
materials–32
Reinforcing steel
3.1.1 Concrete/steel (ferrous
metal)–14
Resilient Flooring
General Information–36
9.2.1 Resilient flooring/
Concrete sub-base–36
9.2.2 Resilient flooring/Wood
panel sub-floor–36
9.2.3 Resilient flooring/Floor
fills and toppings–37
9.2.4 Resilient flooring/Latexbacked rugs and mats–37
Rigid insulation
7.1.4 Vinyl siding /Rigid
insulation–24
7.2.1 Bituminous
membranes/Polyisocyanurate
foam insulation–24
7.3.1 Sealants/Rigid
insulation–28
3
Incompatible Building Materials
Roofing
7.2.1 Bituminous membranes/
Polyisocyanurate foam
insulation–24
7.2.2 Bitumens/Polystyrene
foam insulation–26
7.2.3 EPDM
membranes/Bituminousbased air barrier
membranes and
flashings–26
7.2.4 Roofing
membranes/Heat-applied
roofing products–26
Screws
6.1.1 Metal fasteners/Cedar,
redwood and treated wood
products in exposed
locations–22
Sealants
General Information–26
7.3.1 Sealants/Rigid
insulation–28
7.3.2 Sealants/Vent pipes–29
7.3.3 Silicone sealants, acidcure/Other materials–30
7.3.4 Silicone sealant/
Mirrors–30
7.3.5 Silicone sealants/
General–30
7.3.6 Plumbers putty/
Sunlight–31
7.3.7 Polyurethane
sealant/Polyethylene–31
7.3.8 Polyurethane
sealant/Asphaltic
materials–32
Seismic restraint
5.1.4 Metal strapping seismic
restraint/Hot water
heaters–21
4
Siding
7.1.4 Vinyl siding/Rigid
insulation–24
Wood
9.2.2 Resilient flooring/Wood
panel sub-floor–36
Silicone sealants
7.3.4 Silicone
sealant/Mirrors–30
Wood panel sub-floor
9.2.2 Resilient flooring/Wood
panel sub-floor–36
Smoke alarms
16.1.1 Smoke alarms/Halogen
lighting–40
Wood, treated
6.1.1 Metal fasteners/Cedar,
redwood and treated wood
products in exposed
locations–22
Steel (ferrous metal)
3.1.1 Concrete/Steel (ferrous
metal)–14
Sunlight
7.1.2 Exterior
membranes/Sunlight–23
Surfactants
7.1.1 Housewrap/
Surfactants–23
Vent pipes
7.3.2 Sealants/Vent pipes 29
15.1 High-temperature vent
pipes/Combustion–39
Vinyl siding
7.1.4 Vinyl siding/Rigid
insulation–24
Water heaters
5.1.4 Metal strapping seismic
restraint/Hot water
heaters–21
Windows, vinyl
7.1.3 Peel-and-stick
membranes/Vinyl
windows–24
Wiring
16.1.2 Electrical wiring/CPVC
pipe–40
Wood, cedar and redwood
6.1.1 Metal fasteners/Cedar,
redwood and treated wood
products in exposed
locations–22
Wood knots
9.1.1 Paint/Wood knots–35
Executive Summary
There have long been suspicions that the dramatic increase in the number of products and
materials available for residential construction could result in a far greater incidence of failure due
to material incompatibility. The combination of incompatible materials can result in deterioration
of one or both materials, reducing service life and resulting in additional cost, and causing
inconvenience or performance degradation for both builders and homeowners.
Although incidences of incompatibility surfaced from time to time, they were often lost because
there was no central registry for the recording of material combinations to be avoided. Canada
Mortgage and Housing Corporation (CMHC) initiated a study to research and document examples
of building material incompatibilities. The purpose of this research report is to document and share
information that will help builders, renovators and homeowners avoid unnecessary cost and
inconvenience.
An Advisory Committee comprised of respected building experts representing building officials,
the residential construction industry, government and university research sectors and the wood
and coating manufacturing industries guided the project. The purposes of the committee were to:
a) guide the project by defining the scope and direction,
b) provide input to the project based on experience and knowledge, and
c) assist with the wide distribution of the information at the end of the project.
Extensive research was done to uncover examples of incompatible building materials. Relevant
periodicals, textbooks and Web sites were reviewed and major universities and research facilities
specializing in building materials were contacted. A survey form was distributed to builders,
renovators, architects, specification writers and code officials through their professional associations.
Once the raw data was collected, the examples were screened and reviewed by the Advisory
Committee. Prior to incorporation in the report, each reported case of material incompatibility
was reviewed by a technical expert to ensure the validity of the information in the report.
This report documents 35 examples of building material incompatibilities that can result in
shortened service life, material or system failure, and in some cases, compromise health and safety.
A review of the examples reported shows that some are old problems (for example, dissimilar
metals) that still occur as a result of lack of awareness or failure to foresee ramifications. Others
examples of incompatibility are caused by new generation materials (for example, sealants) and may
occur because of the wide range of chemical formulations of these products and the wide range of
materials they are used with. A simple, standardized labelling system would make it much easier for
builders and renovators to make appropriate sealant selections.
For each example documented in the report, there are likely several others that have not been
reported. This report is a starting point for documenting building material incompatibilities.
5
Introduction
In the past 30 years, residential construction has become much more complex. In addition to the
age-old purpose of providing shelter, residential building design needs to consider energy efficiency,
using materials that minimize effect on the environment, waste reduction and more stringent code
requirements for fire, durability, indoor air quality, sound transmission and moisture and mold
control.
This increase in complexity has been accompanied by a vast increase in the number of materials
that help builders and renovators meet these increasing requirements. The wide range of possible
combinations for building materials, finishes, furnishings and accessories means the chances of a
problematic combination of building materials has increased. Innovation always has an impact and
in some cases, the full ramifications of using new products are not completely understood.
The Canadian Home Builders’ Association (CHBA) and CMHC have been aware of official and
unofficial reports of suspected building material incompatibilities. However, because there has been
no central registry for recording incompatibility problems, it is likely that many problems are not
reported or recorded. This means there is no shared learning among building professionals and
problem material combinations are repeated.
The use of incompatible materials can result in deterioration of one or both materials, reduced
service life, discoloration, or poor adhesion between materials. Technical literature that accompanies
various construction materials and products may identify incompatibility issues, but such
instructions are not always noted. In addition, where several trades are involved, compatibility
issues may be overlooked at the interface of such components as windows, roofing, foundations,
deck coatings and other elements where a number of materials and trades meet.
Purpose
The purpose of this research is to gather and document building material incompatibilities so that
lessons learned in the field can be shared. Prior to this project, the lack of a central registry meant
there was at best very limited sharing of information about lessons learned. Increased awareness
of building material incompatibilities will reduce construction defects to the benefit of builders,
renovators, designers, homeowners and material manufacturers.
Criteria for inclusion
Approximately 100 examples of incompatibility were uncovered through the literature search and
the survey. Only 35 have been included in this report. At the outset of the project, efforts were
made to define incompatibility for the purposes of the final report. It was determined that chemical
interaction would be the main criteria for defining incompatibility and the report would be a
starting point for describing the clearest and most obvious examples of material incompatibility.
Accordingly, this report describes the major examples of incompatibility known to Canadian
builders and renovators as of the first quarter of 2003. Examples that were not included in the
final report were rejected if they:
•
could not be substantiated
•
were a duplicate of a case already in the report
•
violated generally accepted good practice
7
Incompatible Building Materials
Research intent and accuracy
The purpose of this report is to caution builders about possible incompatibility issues that could
arise if certain materials are combined in use. The report is based on concerted efforts to validate
and confirm examples of incompatibility. In no way does this report purport to blame one material
or another for any problems or alleged problems resulting from proven or suspected
incompatibility.
For this reason, CMHC and its agents and consultants provide the information in this report in the
spirit of helping builders and renovators learn from each other’s experience so that they can avoid
callbacks. The report may also serve to help manufacturers make product improvements in response
to applications or circumstances that were not envisioned when a product was conceived.
Causes of material incompatibility
Some of the incompatibility cases reported are well documented scientifically. For example, it has
long been known that the combination of two different metals will result in accelerated corrosion
of one. The science of metallurgy is well advanced and the challenge is to inform builders so that
problems can be avoided. This does not mean that one metal is better than the other–simply that
precautions are necessary in cases where the use of two different metals cannot be avoided. These
types of incompatibilities can usually be identified and substantiated by literature research.
Other instances of incompatibility involve new products or applications of products that were
not expected during product development and testing. Often, these incompatibilities are newly
discovered and are reported by building professionals. In these cases, an incompatibility may not
have gathered enough prominence for its effects to be replicated and documented scientifically.
It is intended that the information in this report will be augmented, corrected, abridged and
updated to include additional information as deemed appropriate.
Physical incompatibilities can occur when materials react differently to temperature. For instance,
if torch-grade roof membranes are installed over self-adhered or spray-applied membranes, the
application heat may cause self-adhered or spray-applied membranes to melt.
Chemical incompatibilities occur when adjacent materials react chemically. For example, the
chemical composition of asphalt roof membranes may cause certain rubber membranes to
decompose.
Moisture, sunlight and temperature are factors that cause rot, corrosion, mold, degradation, loss
of insulating capability, thermal movement, weakening, and distortion–all major focuses of building
science research. These topics fall outside the definition of incompatibility as used in this report.
However, there are indeed grey zones that could not be avoided. For example, the corrosion
rate of one of two dissimilar metals is accelerated by moisture, temperature and salt-laden air.
During the course of the project, attempts were made to differentiate between problems of
incompatibility and those resulting from design and workmanship problems. For example, damp
proofing is applied to concrete foundation walls to prevent transmission of moisture through the
8
Incompatible Building Materials
wall. Damp proofing is adequate for situations where there is not a hydrostatic head on the wall
or to compensate for cracks in the concrete. While it might be said that damp proofing is not
compatible with cracked concrete, it is compatible with concrete. Therefore, this report was
considered to be a quality control issue rather than an issue of material incompatibility.
There are many instances in construction where workers are advised to protect themselves from
fumes, dust and chemicals. For example, exposure to VOCs (volatile organic compounds) emitted
by solvent-based coatings during curing should be controlled. Instances of construction conditions
that are health hazards have not been included in the scope of incompatible building materials.
Builders are advised to take all manufacturers’ recommendations for health and safety precautions
seriously.
In some cases, incompatibility was reported for a specific trade-named product. In such cases, it
was verified that a case applies to a family of products rather than a trade-name product before
being included in the report.
Methodology
Advisory committee
An Advisory Committee (see Acknowledgements, page 49) comprised of respected building experts
representing building officials, the residential construction industry, government and university
research sectors and the wood and coating manufacturing industries was established to:
1. Guide the scope and direction of the project.
2. Identify sources of information for incompatibility problems.
3. Provide advice and assistance for getting the report information to building professionals.
Research
At the outset of the project, a literature search was made that included a comprehensive review of
building and material sources of information. The search focused on Canada but U.S. sources were
also searched. The search words used included: failure, degradation, delamination, incompatible,
incompatibility, premature, deterioration and defect.
The search covered the Internet, builder periodicals such as Fine Homebuilding and the Journal
of Light Construction, literature searches made through the Canada Institute for Scientific and
Technical Information (CISTI) and the Institute for Research in Construction of the National
Research Council and correspondence with a number of industry associations such as the Canadian
Home Builders Association and the National Association of Home Builders Research Center (see
Appendix A, page 45).
The literature search generated 10 of the 35 incompatibility examples that were incorporated into
the final report.
9
Incompatible Building Materials
Survey
A survey form was sent to architects, builders, renovators, building officials, industry associations
and selected individuals to obtain examples of building material incompatibility. Respondents were
asked to describe the material incompatibility problem and, where possible, a solution to the
problem. In many cases, the person who reported the case was contacted for additional
substantiating information.
A sample survey form is located in Appendix B, page 48, for the purpose of:
•
documenting how the survey was made.
•
providing an avenue for readers to report additional incompatibility examples.
•
The survey generated 25 of the 35 examples that were incorporated in the final report.
Screening
Each example was screened to ascertain that the example fell within the meaning of incompatibility.
The screening also determined whether additional confirmation was required or if an example was
a duplicate of one already reported. The results of the screening were submitted to the Advisory
Committee for approval. Prior to inclusion in the final report, examples were confirmed by
a) published information and
b) by one or more technical experts.
In some cases, known incompatibilities resulted from combinations that are permitted by building
codes. In such cases, the example was submitted to the appropriate code officials for review and
action.
Verification
Each of the examples, including the General Information that accompanies some sections, was
reviewed by a technical expert prior to incorporation into the report, to ensure the information
is accurate.
Report
“Section 7–Examples of Incompatibility,” page 13, explains the nature of the material
incompatibility problem, the time frame it takes for the problem to become apparent and, as much
as possible, an explanation of why the materials are not compatible. Each item has a reference title
and each item is explained in more detail in terms of Problem, Reporting source and Solution.
In some cases, a General information section has been added where the problem is broad rather
than specific. For example, dissimilar metals are known to be problematic especially when moisture
is present. Because there are perhaps 20 or 30 metals that can find their way into residential
construction, the General Information explains how the combination of metals can be satisfactory
or unsatisfactory depending on much they differ chemically.
10
Incompatible Building Materials
The report has been organized based on the Masterformat numbering system. Each example, even
though it involves two materials, is reported only in one location, but is cross-referenced to the
other Division (if applicable). (The location of each example was selected to make finding the
information as intuitive as possible for the reader–it is in no way intended to blame one material
or the other.)
For example, “7.1.3 Peel-and-stick Membranes/Vinyl windows” (page 24) is reported in “Division
7–Thermal moisture protection,” page 23. There is also, in “Division 8–Doors and windows,”
page 33, a reference to 7.1.3.
Communication plan
Toward the end of the project, a technology transfer plan was developed to provide the report
to individuals and organizations that assisted with survey responses or technical review. The
information on incompatibility will be available to a wide audience. Hopefully, distribution of
the report will result in more incompatibility examples that can be added to future reports. In
the longer term, the report might be available on the Internet and provide an online mechanism
for adding additional examples of material incompatibility as they arise. The survey form in
Appendix B, page 48, will be used to solicit additional examples of incompatibility.
Trend analysis
The examples reported were assessed as a whole to determine trends in terms of groups of materials
that seemed particularly prone to incompatibility or lessons that could be learn from the reported
examples. See Section Trend Analysis, page 41.
11
Examples of Incompatibility
This section describes the reported examples of incompatible building materials.
Division 1–General Requirements
No reports
Division 2–Sitework
No reports
13
Incompatible Building Materials
Division 3–Concrete
General information
Concrete is a versatile building material, the predominant choice for residential foundations and is
finding increased use for the above-ground structure. Concrete, a proportioned combination of
cement and aggregates, is chemically complex and care should be exercised in the embedment of
metals in concrete. Steel reinforcing is the most common metal embedded in concrete and generally
performs well, but special measures may be required for severe environments.
Other concrete-related reports:
Division 9–Finishes 9.2.1 Resilient flooring/Concrete sub-base (page 36)
3.1.1 Concrete/Steel (ferrous metal)
Problem: Steel is the most common reinforcement used in concrete and normally provides
reinforcing steel with excellent corrosion protection. However, the deposition of de-icing salts on
reinforced garage floors can result in corrosion of the steel. As the steel corrodes, it increases in
volume and causes the concrete to spall.
Reporting source: Literature search
Solution: Concrete structures must be designed to suit the service conditions. For residential
construction, conditions are not usually encountered that require special measures to ensure that
steel corrosion does not damage the concrete. However, garage floors can be exposed to
concentrations of de-icing salts that fall from vehicles.
Corrosion of the reinforcing steel can be controlled if one of the essential elements (steel, oxygen,
water, chloride) is unavailable for the galvanic process that causes the corrosion. In practical terms,
this means
a) coating the steel with a protective cover like epoxy
b) minimizing the porosity of the concrete by using low water-cement ratio concrete
c) providing a good slope and drains to remove salt and water from the surface
d) using a coating or membrane covering to keep the salt solution away from the concrete surface,
or
e) ensuring an adequate concrete cover over the steel reinforcements.
Although each of these measures can work, a combination of two or more increases longevity.
3.1.2 Concrete/Non-ferrous metals
Problem: The embedment of non-ferrous metals in concrete or mortar can lead to either failure of
the metal or damage to the concrete. Embedded aluminum flashing, electrical conduit or structural
members are subject to corrosion in concrete or mortar. The reaction between aluminum and
concrete may cause expansion and cracking of the concrete or mortar. The presence of calcium
chloride (de-icing salts) and moisture increases the reaction rate.
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Incompatible Building Materials
Copper flashing is sometimes embedded in concrete or mortar or both. Embedded copper is
relatively immune to reaction with alkalis in the concrete. However, leaching from rainwater may
bring chlorides from the concrete in contact with the metal and result in corrosion and green
discoloration or runoff. Copper does not react with dry, hardened concrete or mortar or both. In a
similar vein, bronze and brass fittings used for radiant floor heating (hydronic) systems required
protection from concrete (plastic sleeves, for example) while the concrete is curing.
Lead corrodes when in contact with fresh concrete and/or mortar but the reaction ceases if the
concrete has cured and stays dry. Corrosion of embedded lead flashing in mortar joints will usually
result in the production of a lead oxide, a white discoloration. When lead is only partially
embedded, corrosion occurs because the part of the strip exposed to the concrete has a different
electrical potential than the section exposed to air. Gradual corrosion and disintegration of the
embedded lead will result.
Zinc is highly reactive with alkalis and will deteriorate to some degree upon contact with fresh
concrete or mortar or both. The reaction is limited, due to a corrosive film that forms on the outer
layer of the zinc. Zinc will not react with dry, seasoned concrete or mortar or both. Zinc corrosion
may also occur when galvanized iron, in the form of flat or corrugated sheets and rebar, comes in
contact with fresh concrete and/or mortar. Galvanized iron is coated with zinc, and will react with
moisture and chlorides in the concrete and/or mortar and can result in cracking of the concrete or
mortar or both.
Reporting source: Literature search
Solutions: Care is required in considering the embedment of non-ferrous metals in concrete,
especially in wet conditions.
•
Aluminum Coating the aluminum with bituminous paint, impregnated paper or felt, plastic,
or an alkali-resistant coating will prevent or sharply reduce the corrosion.
•
Copper Chloride admixtures should not be used in concrete if contact with copper is expected.
•
Lead The concrete-embedded portion should be coated with epoxy, varnish, asphalt or pitch.
•
Zinc Embedded galvanized iron should be protected with epoxy, varnish, asphalt or pitch.
Division 4–Masonry
No reports.
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Incompatible Building Materials
Division 5–Metals
General information
Galvanic corrosion (also called “dissimilar metal corrosion”) is corrosion damage that occurs when
two dissimilar materials are coupled in a corrosive electrolyte. When a galvanic couple forms, one of
the metals in the couple becomes the anode and corrodes faster than it would by itself, while the
other becomes the cathode (Figure 5.1).
Figure 5.1: Corrosion of a cadmium plated washer in contact with
a stainless steel screw
Galvanic corrosion alters the surface, making it more susceptible to chemical reaction with
the atmosphere. In extreme cases, the galvanic corrosion can cause serious mechanical and
structural damage to the materials involved. Homebuilders may use metals in many different
applications–metal roofing and siding, windows, framing, fasteners, ductwork, electrical systems
and water and waste water piping systems. In addition, metals are important components of
appliances, computers and furnishings. Metal failures -corrosion, oxidization or rusting–may
result in inconvenience or callbacks, shorten service life and may even compromise safety.
Therefore, a basic primer on the factors that cause metal failures and how to slow or stop
deterioration is provided here.
Any two different metals in contact can generate contact potential due to their differences in
electrical conductivity, resulting in a galvanic reaction. In many applications, the reaction is
minimal but in some cases, the deterioration of one of the two metals can be rapid. The speed
of the reaction is dependent on two factors:
16
Incompatible Building Materials
a) the electrode potential of the two metals in the electrochemical series, and
b) their surrounding chemical environment.
In general, the further apart the materials are in the galvanic table, the higher the risk of galvanic
corrosion. For example, installing copper (noble number 55) water piping through steel studs that
are galvanized with zinc (noble number 4) results in strong galvanic action. For this reason,
building codes require plastic grommets to keep the two metals apart. Conversely, the closer one
metal is to another in the table, the more compatible they will be.
Figure 5.2 is the galvanic table simplified to show only those metals that are likely to be present in
residential construction. At the left of the figure are the active or anodic metals, the ones that are
sacrificed when in contact with metals that have a lower “noble” number. Zinc, with a low noble
number, is often used as a sacrificial (galvanic) protection for steel. As galvanic action progresses,
the zinc is gradually sacrificed and for this reason, the thicker the zinc coating is, the longer
galvanized steel will perform. For example, connecting metals with widely different electrical
properties can lead to loss of electrical conductivity as one of the metals in the connection
corrodes. For example, copper wire should not be connected to aluminum wire or fixtures.
Figure 5.2: Noble numbers
Environment is the second factor that affects the speed of the reaction. The effect of galvanic
corrosion is increased in the presence of an electrolyte, such as water or a salt that act as a transfer
medium for the electrons. For this reason, corrosion is a greater problem for exterior applications
such as roofing, cladding, windows, doors and air conditioning units. However, water is also in
17
Incompatible Building Materials
contact indoors with water piping and anywhere where water leakage is a possibility, for examples,
under washing machines or dishwashers. In addition, high humidity or condensation increases the
potential corrosion problem. Here are two examples:
1. Built-in galvanized rain gutters are reported to disintegrate after as little as 13 years exposure
to west coast moisture and salt air.
2. Asphalt-backed copper flashing installed at the base of brick veneer is reported to disintegrate
after 25 years exposure to west coast moisture and salt air.
De-icing salts are a major corrosion problem for concrete structures, such as bridge decks. Even
around the house, de-icing salts can accelerate corrosion in places where salts are deposited by
vehicles or foot traffic such as walkways, garage floors, thresholds and the underside of steel entry
and garage doors.
Types of protection
There are several common methods of protecting metals (Table 5.1).
Sacrificial protection
Hot-dip galvanizing is the process of immersing the steel object to be protected in molten zinc.
The thicker the zinc coating is, the longer the steel will be protected from corrosion. For example,
it is estimated a 1.7-mil zinc coating exposed to the weather will last 18 years in a suburban
application and a coating of 3.4 mils will last 30 years. However, thicker coatings are prone to
spalling away from the metals they are intended to protect if the host metal has not been properly
prepared (for example, by pickling).
Electroplating is the deposition of a metallic coating on an object by immersing it in a solution
that contains a salt of the metal to be deposited. Electroplated coatings may perform a protective
function, as in the case of electroplated fasteners, or a decorative function, as in the case of plating
a lower-cost metal with gold and silver. In general, electroplated nails and screws will have a thinner
layer of sacrificial metal than the hot-dip process and therefore the life expectancy of the fasteners
will be lower.
Table 5.1: Metal protection techniques
Protection method
Strengths
Weaknesses
Paint
Easy to apply, inexpensive
Short life, easily damaged
Grease, oil
Inexpensive
Short life, easily removed
Corrosion resistance
Excellent protection when
alloys (stainless steel, brass properly selected
etc)
Expensive
Hot-dip galvanizing
Long-term protection, readily
available
Changes thread dimensions on
screws and bolts
Electroplating
Inexpensive, readily available,
moderate protection
Easily damaged, not
recommended for use with
treated wood
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Incompatible Building Materials
Coating Non-metallic coatings may be used to provide corrosion resistance. For example, epoxy
coated rebar has become common in commercial construction and epoxy-coated screws are widely
used for deck construction. Any coating (for examples, paint, oil, Teflon®, wire sheathing) that
keeps oxygen away from metals will curtail corrosion for as long as the barrier remains intact.
Other metal-related reports
Division 3–Concrete
• 3.1.1 Concrete/Steel (ferrous metal) (page 14)
•
3.1.2 Concrete/Non-ferrous metals (page 14)
Division 6–Wood and plastics
• 6.1.1 Metal fasteners/Cedar, redwood and treated wood products in exposed locations (page 22)
5.1.1 Copper tubing/Aggressive soils
Problem: Copper is very resistant to deterioration in buried conditions. However, there are
conditions that can cause copper to corrode when it is exposed to certain soils:
•
abnormally aggressive soils
•
stray AC and DC current in the ground
•
faulty design
•
galvanic reaction involving dissimilar materials.
The soil conditions that result in copper corrosion are very complex and not entirely understood.
However, corrosion is most often associated with:
•
Soils high in sulfate and chloride content and having a high capacity to retain water, and
moderate to high annual rainfall (76 cm or 30 in. or more).
•
Soils that have large quantities of organic matter (particularly soils that contain organic acids
or that support active anaerobic bacteria).
•
Most cinder fills, either because of the sulfides present or the galvanic action created by the
carbon particles in the cinders.
Soils such as clay, sand, gravel, loam, and chalk seldom possess the combination of properties
associated with corrosion.
Failures from poor design usually occur where bent copper tube passes through a concrete slab. If
the pipe is carrying heated liquid, thermal stresses may cause fatigue and cracking on the underside
of the tube at the underside of the slab. It is also known that copper embedded in concrete is
normally cathodic in relation to copper embedded in soil. This can result in a weak galvanic
reaction if water is present.
19
Incompatible Building Materials
Reporting source: This problem has been reported in the Journal of Light Construction and
through Internet chat forums.
Solutions:
1. Use Type K (heavier wall) copper pipe recommended for underground use or use a sleeve.
2. For aggressive soils, ensure trenches for copper pipe are not collectors for surface runoff or
septic drainage systems. For those areas where the soils are known to be aggressive, the pipe can
be encased in selective backfill. However, this method will be affective only if the drainage for
the aggressive soils can be kept away from the pipe. Or, use polyethylene coated copper pipe.
3. Use di-electric fittings for connection to non-copper pipes.
4. For copper pipes carrying hot liquids that penetrate concrete slabs, allow for thermal expansion
of the pipe below the slab or install the pipe in a sleeve.
5.1.2 Copper pipe/Plumbing
Problem: Copper tubing can also develop pinholes without being in contact with the soil. In the
U.S., there are reports of indoor copper piping developing green spots on the outer surface followed
by dripping from these locations. This problem has been reported in groups of houses less than
10 years old.
This internal corrosion is attributed to either aggressive water or the use of incompatible plumbing
flux. The water is considered aggressive if the water has a pH value lower than 7.0 (acidic) and high
levels of dissolved carbon dioxide and oxygen or sulphates. Acid water is known to be corrosive to
copper–in fact, ANSI/NSF Standard 61 certifies copper for use only where the pH of the water is
6.5 or higher. Although highly alkaline water pH (higher than 7.0) can also be corrosive, such
water is so unpalatable it is rarely used as a water source.
The problem could also result from the use of flux that is not as flushable as that stipulated in
ASTM B-813.
Reporting source: Journal of Light Construction, Internet chat forums, B.C. architect.
Solution: This problem is rare and not yet well understood. It poses a dilemma–particularly for
rural housing where the water chemistry is not controlled by a public utility. At this point, it is
thought the occurrence of copper pipe pitting can be reduced by using the correct flux, not using
an excessive amount of flux, flushing the pipe properly–for 10 minutes at full flow–after
installation, and by not allowing pipes to sit idle for a long period of time before they are brought
into regular use.
5.1.3 Copper flashing/Metal fasteners
Problem: Copper flashing fastened with non-copper fasteners is subject to galvanic action and
corrosion. While galvanic corrosion is the most familiar type of metallic deterioration, it is the most
neglected from the standpoint of anode/cathode area relationships. For example, galvanic corrosion
can occur when two metals that are far apart in the electrochemical series (Figure 5.2 ) are
20
Incompatible Building Materials
combined in a moist, corrosive environment building assembly. When moisture is present, a
galvanic cell is set up, causing the less-noble metal to corrode. This galvanic corrosion phenomenon
is common in copper-aluminum roof assemblies. The aluminum (the less-noble material) fasteners,
gutters and downspouts tends to be dissolved by the copper (the more-noble material) flashing on
roofs.
Reporting source: Trade associations and builders
Solution: Use copper nails or screws for fastening copper flashings.
5.1.4 Metal strapping seismic restraint/Hot water heaters
Problem: For areas subject to earthquakes, the National Building Code stipulates that hot water
tanks be restrained by strapping to prevent movement during an earthquake. Galvanic action
between the tank and the strapping could negate the effectiveness of the strapping to restrain the
tank in the event of earthquake. This is a specific example of dissimilar metals that could lead to
structural failure.
In one case, it was reported that seismic support strapping had corroded after 1 1/2 years due to
galvanic reaction with an area of the hot water tank where the paint had been damaged. This may
not be a common occurrence but shows how incompatibility can result not only in inconvenience
or shortening of life span, but can also result in unsafe conditions.
Reporting source: B.C. building official
Solution: Either the strapping metal should be similar to the tank casing, or the two metals should
be separated by covering the strapping with a sheathing material (garden hose was the solution
suggested).
21
Incompatible Building Materials
Division 6–Wood and Plastics
Other wood-related reports:
•
Division 9–Finishes
•
9.1.1 Paint/Wood knots (Page 35)
6.1.1 Metal Fasteners/Cedar, redwood and treated wood products in exposed
locations
Problem: Unprotected fasteners made of metals susceptible to corrosion should not be used with
wood products treated with copper-based preservative (such as ACQ—ammoniacal copper quat,
CCA–chromated copper arsenate and copper azole) in wet locations because the copper in the
preservative will accelerate the oxidizing effect of water on the metal. In addition, types of wood
that have natural resistance to decay, such as redwood and the cedars, contain natural chemicals
that can also cause premature failure of nails and screws. Untreated fasteners and even lightlygalvanized fasteners suffer a loss of cross-section and ultimately fail.
Reporting source: This incompatibility problem has been well documented in information
produced by the Canadian Wood Council, Forintek Canada Corp. and the Canadian Institute for
Treated Wood.
Solution: In general, hot-dipped galvanized, coated fasteners recommended by the preservative
manufacturer or stainless steel fasteners should be used with preservative treated wood.
Building codes require that fasteners used for wood foundations be hot-dipped galvanized or
stainless steel conforming to CSA B111, Wire Nails, Spikes and Staples. For cedar shingle or shake
roofs and siding, the Western Red Cedar Lumber Association recommends the use of hot-dipped
galvanized, aluminum or stainless steel fasteners.
22
Incompatible Building Materials
Division 7–Thermal moisture protection
General information
Moisture management is a very important aspect of building design and performance.Therefore, it
is not surprising that a fairly large number of building material incompatibilities were reported for
this division.
There are many materials that are affected by heat (cold), moisture and ultraviolet light that have
not been included in this section because their deterioration is affected by environmental
conditions rather than by other building materials.
7.1 Envelope
7.1.1 Housewrap/Surfactants
Problem: There are reports of changes in the properties of spunbonded polyolefins due to
surfactants. The surfactants can originate from
a) certain types of wood species
b) additives mixed with the stucco to improve workability during installation.
The primary function of a housewrap or sheathing membrane is moisture control. Therefore, any
breakdown of the moisture penetration control barrier offers the possibility of water entry into the
building envelope.
Certain chemicals can cause the loss of water repellency of spunbonded polyolefin housewraps.
These chemicals, called surfactants, are typically ingredients in soap.Surfactants can reduce the
water repelling capability of housewrap by changing the viscosity of water.
The tannins that make species such as cedar and redwood durable can also act as surfactants that
cause housewrap to become more permeable to water. In addition, certain additives that improve
the workability of stucco can also act as surfactants and lower the effectiveness of housewrap
moisture barriers.
Reporting source: Building science researchers, builders
Solution: For wood species with high tannin content, install the cladding over strapping so that the
cladding is not in direct contact with the housewrap. Another solution (probably less reliable) is to
backprime the siding.
For stucco, a building system that separates the stucco from the housewrap should always be used.
7.1.2 Exterior membranes/Sunlight
Problem: Building paper and housewraps are installed in wall assemblies to prevent rain
penetration. Any breakdown of the rain penetration control barrier offers the possibility of water
entry into the building envelope. Building papers and housewraps are not designed to withstand
long-term exposure to ultraviolet radiation (sunlight).
23
Incompatible Building Materials
Therefore, the planning of construction should ensure that building paper or housewrap membrane
be covered with cladding in the period of time recommended by the membrane manufacturer. In
addition, prolonged exposure increases the potential of tears from wind and construction activity.
Reporting source: Product evaluation reports
Solution: All Canadian Construction Material Centre (CCMC) product evaluation reports verify
sheathing membrane performance based on a 60-day exposure. However, because the durability of
exposed housewrap varies with climate and exposure, it is good practice to cover the membrane
soon after installation and to check the manufacturer’s recommendations.
7.1.3 Peel-and-stick membranes/Vinyl windows
Problem: Certain asphalt-based peel-and-stick membranes used to seal sheathing membranes to
vinyl doors and windows may react with the vinyl. The reaction results in the asphaltic membrane
running and staining exterior surfaces. The asphaltic material is a first generation peel-and-stick
product (4-in.-100-mm and 6-in.-150-mm rolls). In addition to staining the vinyl, it is likely the
reaction also damages the window or door frame. Staining shows itself within one year of
installation. It is not known if or when failure of the joint will occur.
Reporting source: B.C. architect
Solution: Use new generation peel-and-stick products or use rubber products and check with the
window manufacturer for compatibility.
7.1.4 Vinyl siding/Rigid insulation
Problem: Vinyl siding applied directly over EPS or XPS (expanded or extruded polystyrene) rigid
insulation is a plastic-on-plastic arrangement. Vinyl siding has a high coefficient of expansion so,
especially in the spring and fall, there is a lot of movement of the vinyl siding as temperatures
fluctuate. The movement of the siding over EPS or XPS insulation causes squeaking noises that
are audible through walls.
Reporting source: Manitoba EPS manufacturer
Solution: A layer of housewrap or building paper should be installed between the vinyl siding and
the EPS or XPS insulation to isolate the materials.
7.2 Roofing
7.2.1 Bituminous membranes/Polyisocyanurate foam insulation
Problem: This problem is reported for large, low-slope roofs but could apply to roofs on residential
buildings. The National Roofing Contractors Association (NRCA) has reported incompatibility
problems between hot-applied bituminous membranes. Although the vast majority of roof
assemblies that include polyisocyanurate insulation have performed successfully, problems have
been encountered that can result in some of the following failure modes:
•
facer-sheet delamination
•
cupping or bowing
24
Incompatible Building Materials
•
shrinkage
•
crushing or powdering.
It is not certain why the problem sometimes occurs, but it is thought that improper curing of the
foam insulation board prior to installation makes it more prone to damage from the hot-applied
bituminous membranes.
Reporting source: The National Roofing Contractors Association (NRCA) Bulletin 2000-3,
March 2000
Solution: NRCA recommends that designers specify cover board over polyisocyanurate insulation
in all low-slope membrane roof systems. The use of a cover board should help to reduce problems
whether directly related to the manufacturing process or due to other causes.
Insulation cover boards should be a minimum ½-in (13-mm) thick and be composed of any of the
following:
•
glass-faced siliconized gypsum board
•
perlite board
•
wood-fibre board
•
glass-fibre board
•
mineral-fibre board
When selecting a suitable cover board, designers should consider the characteristics of the specific
roof assembly and take into account the cover board’s compatibility with the assembly.
Using a suitable cover board over polyisocyanurate insulation in low-slope membrane roof
assemblies provides the following benefits:
•
It separates the membrane from the polyisocyanurate insulation, reducing the possible effects of
facer-sheet delamination, edge cavitation, cupping or bowing, shrinkage and crushing or
powdering of the polyisocyanurate insulation.
•
It allows for installation of the insulation board layers with staggered board joints, a practice
known to reduce stresses on the membrane and improve a roof assembly’s overall thermal
performance.
•
It may be required to achieve a fire-resistance classification for a roof assembly.
In addition, NRCA is seeking improvements to ASTM C 1289, Standard Specification for
Faced Rigid Cellular Polyisocyanurate Thermal Insulation Board including the establishment of
a requirement for curing time prior to shipment, and changes in the standard’s values for
compressive strength, dimensional stability and R value determination.
25
Incompatible Building Materials
7.2.2 Bitumens/Polystyrene foam insulation
Problem: Bitumens and some adhesives can cause polystyrene insulation to disintegrate (see 7.3.1
Sealants/Rigid insulation, page 28). Bitumens can also be destructive to single-ply roofing
membranes. This incompatibility may occur where a new replacement roof abuts an older roof.
Reporting source: B.C. architect, architectural journal
Solution: With new and replacement roofing projects, it is important to ensure that polystyrene
insulation is covered with an approved panel to keep it separate from bitumens and other solventbased materials.
7.2.3 EPDM membranes/Bituminous-based air barrier membranes and
flashings
Problem: EPDM (ethylene-propylene-diene monomer) roofing membranes have been used
successfully for the past 30 years on large flat and low-slope roofs. However, the EPDM membrane
is prone to becoming brittle and cracking where it contacts bituminous-based membranes and
flashings. This is most likely to occur at roof edges and parapet walls.
Reporting source: Alberta architect
Solution: Galvanized-metal transition flashing should be installed between EPDM membranes and
any bituminous-based membranes and flashings.
7.2.4 Roofing membranes/Heat-applied roofing products
Problem: Torch-applied roofing materials can cause damage to peel-and-stick roofing membranes
or to foam insulation.
Reporting source: Alberta architect
Solution: Keep heat away from non-heat resistant materials or shield the heat-sensitive materials
from heat.
7.3 Sealants
General information
A sealant is a material intended to inhibit the passage of air and water in joints where movement is
expected. Ability to accommodate movement is the most important property of sealants. However,
a sealant can only accommodate movement if it is able to adhere to the surfaces it is sealing. After
movement accommodation and adhesion, hardness and resistance to weather are important
considerations.
Because there are so many types of sealants and because their use has become commonplace with so
many different materials, a basic understanding of sealants will help avoid compatibility problems.
Here are some basic guidelines for this complex family of building materials:
26
Incompatible Building Materials
•
Low-movement capability sealants (3 to 5%) are 1-part oil-based or latex (acrylic). Mediummovement capability sealants (7 to 13%) are 1-part butyl or acrylic (solvent based). Highmovement capability sealants (15 to 25%) are 1- or 2-part polysulfide or urethane or silicone.
•
High-movement-capability sealants are more expensive and are used in demanding commercial
and industrial applications such as for high-rise buildings and bridge deck sealants where
accessibility is limited and the cost of failure is high. In addition to high movement capability,
such sealants are usually longer lasting and stay flexible and adhere better than lower quality
sealants. Generally, residential construction will entail low and medium movement capability
sealants.
•
Silicone sealants provide good performance for residential applications. Builders should be
aware that some manufacturers produce so-called “siliconized” sealants. These products contain
a small fraction of silicone and therefore they do not provide the same good performance
characteristics as true silicone sealants. A siliconized acrylic or siliconized butyl should be
considered as having the same properties as ordinary acrylic or butyl sealants.
•
Some surfaces may require a primer in order to accept a certain sealant. Primers are not
commonly available in the consumer market, and the consumers should choose those sealants
that generally possess unprimed adhesion. Contractors can typically obtain needed primers and
thus have a greater variety of sealants suitable to the various applications.
•
The durability of a sealant depends on the application conditions, the conditions in which the
sealant will serve (temperature, UV radiation, wind, rain and atmospheric pollutants) and the
suitability of the sealant for the materials to be sealed and the expected range of movement.
A sealant should be selected that best suits the service conditions.
•
A caulk is an oil-based sealant that has relatively low movement capability, usually less than
five per cent.
•
In general, silicone sealants are the most durable to heat and weathering and least amenable to
painting. Silicone sealants can only be overtopped with another silicone sealant and cannot be
painted.
•
Polysulfides and polyurethanes are not recommended for critical glazing applications where
sealants are exposed to full sunlight.
•
Each manufacturer has different formulations so check compatibility for your most common
applications. Then, select a group of sealants that suit your applications and stay with them.
•
Use Table 7.1 as a general guide for sealant selection.
27
Incompatible Building Materials
Table 7.1: Sealant compatibility and adhesion
Lowmovement
capability
Mediummovement
capability
Sealant Type OilLatex
Butyl
based (acrylic) 1-part
1-part 1-part
Substrate
Aluminum,
anodized
Aluminum,
mill finish
Brick
Concrete
Glass
Metal,
painted
Stainless
steel
Steel,
galvanized
Stucco
Wood,
painted
Wood,
stained
Wood,
unfinished
Acrylic
(solventbased)
1-part
High-movement capability
Polysulfide Polysulfide Urethane Urethane Silicone Silicone Silicone
1-part
2-part
1-part
2-part
acid
neutral base
cure
cure
cure
x
x
x
x, p
x, p
x
x
x
x
x
x
x, p
x, p
x, p
x
x
x
x, p
x
x, p
x
x
x, p,
I
x
x
x
x
x
x
x
x
x
x
x
x
x
x, p
x, p
x
x
x
x
x, p
x, p
x
x, p
x
x
x
x
x
x
x
x
x
x
x, p,
I
x, p,
I
x
x
x, p
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x, p
x, p
Table Adapted with permission from: Cascade Sealants, Portland Ore
Notes: x-likely good performance; p-primer needed; I, suitable for water-immersion application
7.3.1 Sealants/Rigid insulation
Problem: Solvent-based sealants (or adhesives) cause the degradation of polyethylene or polystyrene
foam insulation. Sealant is sometimes used in the joints between panels to prevent the passage of air
and water. Sealant is also used to provide air barrier continuity at the intersection of polystyrene
and the air barrier material. Polystyrene panels may be attached to the structure with mechanical
fasteners or, as in the case of attachment to concrete foundation walls, with adhesives. Usually,
sealants and adhesives have different properties that do not make them interchangeable.
There are two types of polystyrene (expanded and extruded) used for house insulation. Expanded,
or moulded, polystyrene is commonly called beadboard and has a lower R value and is less
expensive than extruded polystyrene because of its lower density. Both types of polystyrene
insulation have the advantages of high R value, good moisture resistance, and high structural
strength.
28
Incompatible Building Materials
The material safety data sheet from a major manufacturer notes that polystyrene is incompatible
with aromatic hydrocarbons and other petroleum-based compounds. Silicones are typically
compatible with polystyrene. However, the manufacturer stresses it is not a maker of sealants
and adhesives and has no ability to control formulations. Therefore, it makes no specific
recommendations for sealants and adhesives that are compatible with its polystyrene insulation.
Reporting source: Material safety data sheet and other sources
Solution: There are many types of sealants (Tables S1 and S2) and there are several types of sealants
and adhesives that are not solvent-based. For residential construction, use latex (acrylic) butyl,
silicone sealants or adhesives with polystyrene rigid insulation.
7.3.2 Sealants/Vent pipes
Problem: Manufacturers of Type B vents used for venting natural gas or liquid propane Category I
appliances affix paper labels to the B-vent pipe sections to identify the type, size and code
compliance for the pipe.
Where the assembly pierces the roof, flashing is placed around the vertical pipe section and a storm
collar is placed over this joint. To make the assembly watertight, the joint between the flashingstorm collar and the pipe requires the application of a flexible sealant.
Because the paper labels are applied in random locations on the pipe and because the positioning
of the protruding length of pipe within the flashing assembly depends on several factors, occasions
arise where the paper label lies in the area that will be sealed (usually with silicone sealant).
Although the seal may seem adequate at first, experience shows that the sealant bond at the paper
label will quickly fail, allowing water to enter the roof through the B-vent assembly.
Figure 7.1: Chimney label
Sealant
Storm collar
Flashing
29
Incompatible Building Materials
Reporting source: B.C. construction management firm
Solution: Installers should ensure that the paper label, including the adhesive, is removed prior to
sealing if it is in the region to be sealed. In the longer term, this problem should be brought to the
attention of vent manufacturers so that a non-problematic labelling system can be introduced.
7.3.3 Silicone sealants, acid-cure/Other materials
Problem: There are two types of silicone sealants–acid-cure and neutral cure. Acid-cure sealants
contain acetic acid and cure by emitting the acid and give this family of sealants a vinegar-like
smell. Acid-cure silicones are very economical, commonly available and adhere well to most
surfaces. The acetic acid in these sealants is aggressive to many materials including epoxies,
concrete, mortar, many types of fasteners and steel.
Neutral-cure sealant cures by reacting with moisture in the air. They are typically slightly more
expensive (10 to 50 %) than acid-cure silicones and do not adversely affect the materials that are
susceptible to acid-cure sealants.
Reporting source: B.C. window manufacturer
Solution: There are many types and formulations of sealants (see Sealants–General Information,
page 26). Have a basic understanding of the types of sealants, their strengths and weaknesses, and
choose accordingly.
7.3.4 Silicone sealant/Mirrors
Problem: Silicone-based sealants and adhesives cause the degradation of the backing or mirrors
in applications where mirrors are affixed to wall surfaces with acetic-cure silicone adhesives.
The data sheet for this family of silicones states:
“Not recommended for structural glazing or insulating glass glazing, concrete and stone expansion
joints, horizontal decks, patios, driveway or terrace joints where abrasion is possible. Not
recommended for surfaces with special protective or cosmetic coatings such as mirrors, reflective
glass, Teflon-coated, polyethylene or polypropylene surfaces. Not recommended for use on
concrete, marble, limestone, lead coated surfaces, submerged joints (swimming pools), plazas,
decks, pavements.”
Reporting source: Builders chat line.
Solution: Do not use acetic-cure sealants or adhesives to affix mirrors. Use specially-formulated
mirror mastics and take the usual precautions to ensure the surfaces to be joined are dry and clean.
One maker of asphalt-based mirror mastic claims to make a product that gives “a strong permanent
bond that remains flexible, yet absorbs movement caused by normal vibrations or thermal changes”.
Neutral curing silicones have a good history of success in this application. However, in each
situation the sealant manufacturer should be contacted to confirm suitability.
7.3.5 Silicone sealants/General
Problem: Silicone sealants are ideal for some applications, but there are some restrictions that need
to be explained.
30
Incompatible Building Materials
•
Painting–Silicone sealants do not hold paint and therefore they should not be used where
painting is a requirement.
•
Re-sealing–Other types of sealants do not adhere to silicone sealant. Therefore, use only
a silicone sealant over top an existing silicone sealant.
•
Ponding locations–Typically, a primer should be applied for sealants used in ponding locations,
especially on concrete where a barrier primer is needed.
7.3.6 Plumbers putty/Sunlight
Problem: There is a wide range of methods used by electrical and mechanical trades for sealing
electrical and gas service stub-outs for rooftop mechanical equipment. A lead sleeve is sometimes
used by the roofer for the penetration through the roof membrane. Some mechanical installers
crimp the lead sleeves and “temporarily” seal the penetration with electrical tape. Other installers
pack plumbers putty between the cable and pipe penetrations and the sleeve, or in some cases, duct
sealant is used. All these methods are temporary solutions that are not capable of withstanding the
ultraviolet (sunlight) and temperature change of exterior locations. For example, plumbers putty
is a linseed oil-based material inadequate for rooftop stub-out connections where vibration and
weather exposure is extreme. After approximately one year, plumbers putty shrinks and becomes
hard with no resiliency for movement. After approximately two to three years, it crumbles away
from the joint leaving the sleeve and penetration exposed to weather and rain penetration.
Reporting source: B.C. construction management firm
Solution: Remove existing putty, tape or other temporary sealants from electrical and mechanical
stub-out joints. Plumbers putty and electrical tape commonly leave oil and residue that prevents
good bonding for the permanent sealant. The surfaces to be sealed must be thoroughly cleaned
with solvent and dried before the application of a high-performance polyurethane sealant.
7.3.7 Polyurethane sealant/Polyethylene
Problem: It is reported that (poly)urethane sealant does not adhere well to polyethylene sheet
material. Although (poly)urethane sealants have excellent adhering properties in most cases, the
adhesion to polyethylene films is very poor. In some installations, the sealant has delaminated after
six months of service even though the adherence seemed good at the time of installation.
There is normally very poor adhesion between (poly)urethane sealants and polyethylene sheet. For
this reason, polyethylene is the most commonly used bond breaker behind (poly)urethane sealants
(as well as other sealants). An initial adhesion occurs as a result of the contact of the sheet to a
viscous liquid. Then as the sealant cures to a rubber and gets harder, the adhesion based on viscous
fluid contact decreases. There are no chemical reactions between the (poly)urethane sealant and the
sheet polyethylene and thus it is understandable that there is only mechanical adhesion and this is
lost as the sealant continues to cure and harden.
Reporting source: B.C. construction management firm
Solution: To maintain airtightness across air barrier joints, sealants must have a long service life
without hardening or cracking with age and be compatible with adjoining materials.
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Incompatible Building Materials
The CSA standard for the construction of permanent wood foundations stipulates the types of
sealants used to seal the exterior polyethylene moisture barrier as follows:
•
CAN/CGSB-19.13 Sealing Compound, One Component, Elastomeric, Chemical Curing
•
CGSB 19-GP-14M Sealing Compound, One Component, Butyl-Polyisobutylene Polymer Base,
Solvent Curing
For non-structural applications, use acoustical sealants or adhesives specifically designed for
polyethylene air barriers.
7.3.8 Polyurethane sealant/Asphaltic materials
Problem: Asphalt roofing materials contain solvents that can damage (poly)urethane sealants. The
asphaltic materials contain solvents and plasticizers that dissolve and discolour urethane. The point
of contact of asphalt materials with (poly)urethane sealants will result in discolouration of the
sealant, eventual delamination of the sealant and, possibly, the softening and deterioration of one or
both materials.
Reporting source: B.C. construction management firm
Solution: When sealing to asphaltic roof membranes, use sealants and adhesives approved by the
membrane manufacturer.
32
Incompatible Building Materials
Division 8–Doors and windows
No reports
Other door and window-related reports:
Division 7–Thermal moisture protection
•
7.1.3 Peel-and-stick membranes/Vinyl windows (page 24)
33
Incompatible Building Materials
Division 9–Finishes
9.1 Coatings
General information
The use of paint, stain, varnish and other coating materials to provide colour and protection for
surfaces is a broad subject. Numerous books, Web sites and articles deal with the subject. The
durability of coatings is a combination of:
•
good surface preparation
•
good application techniques
•
selection of a coating with the best characteristics for the application.
This section does not deal with all the ways coatings can fail, but will list some coating
incompatibility problems particular to residential builders. Some specialty coatings may damage
other coatings or materials. Therefore, it is important for the painter to ensure the product
selected is appropriate for the application. The product label will give important information
about application conditions, including surface preparation, temperature, curing times and times
between recoats. Taking liberties with these directions could result in performance problems.
It is important to note that paint will perform well only if it is applied at temperatures above the
recommended minimum application temperature. In the rush to complete autumn projects,
coatings are sometimes applied to substrates that are too cold for successful application and
performance, including interior coatings applied before the building’s heating system is activated.
Although water doesn’t freeze until the temperature drops to 0°C (32°F), it is not correct to assume
that latex paints can be applied down to that temperature. In fact, the minimum temperature for
latex paint to cure adequately is 10°C (50°F).
Latex paints applied to surfaces below 10°C (50°F) will result in early failure of exterior coatings
and poor washability for interior painted surfaces. Latex paint must be applied in the temperature
range recommended by the manufacturers and for the curing time of the coating (usually two hours
for latex paints and four hours for alkyd paints). In addition, paints specially formulated for low
application temperatures can be used but these also have temperature limitations that must be
respected.
It is general practice in new construction for painting and related touch-ups and repairs to be
completed just before the building is turned over to the owner. The colour of latex paint is affected
by the temperature of the surface to which it has been applied. If painting is done in the spring or
fall, when the temperature of the building interior is low, for example, 10 to 15°C (50 to 60°F) ,
and touch-ups are done at a higher temperature, the result will be two different colours from the
same can. The best practice is to apply paint at or above the minimum recommended by the
manufacturer. If these instructions are not followed, it is likely that touch-up paints will have to be
colour-matched to wall colour.
34
Incompatible Building Materials
To maximize production, many painters use spray equipment to apply latex paints. The application
may be spray alone, or spray followed by rolling to smooth and texture the surface. Because of the
high pressures required to force the paint through the spray tip, colour changes take place during
the application. Therefore, colour irregularity may occur between spray applications and subsequent
touch-ups and repairs. Extra paint should be run through the spray gun and saved for touch-up and
repair purposes. By doing this, any colour variation resulting from spray pressurization will apply
equally to the application coat and subsequent touch-up.
The application of alkyd (oil-based) paints at low temperatures–below 10°C (50°F) can cause loss
of gloss if the coating is exposed to moisture (dew, fog, rain) during the curing process but they are
less subject to damage when applied at low temperature than other coating products. When applied
in low temperature, alkyd paint dries very slowly, but will eventually cure. When recoating in cold
weather, longer dry times (48–72 hours) may be required to prevent wrinkling of the previous coat.
The application of alkyd paints at temperatures below 10°C (50°F) may result in poor performance
in the form of poor gloss. In addition, slower curing time means a longer period of exposure to
damage from abrasion and wind-carried particulates.
9.1.1 Paint/Wood knots
Problem: Due to the high concentration of resins in wood knots, painting over knots will often
result in discoloration of the paint.
Dark-coloured paints applied to exterior wood surfaces with a southern or western exposure can
result in the dark surface absorbing the summer heat, liquefying the resin in the knots, and causing
the paint to wrinkle or peel.
Reporting source: Paint industry expert
Solution: Wood knots should be primed with a sealer prior to top coating with paint. Orange
shellac is still a good material for priming knots or sap streaks in wood. Shellac loses its drying
ability as it ages so use a test patch to ensure the shellac will dry. White shellac is not as effective
and has a short shelf life. Proprietary primers that are shellac- (alcohol) based can also be used.
Most of the varnishes sold today contain polyurethane, which is not compatible with shellac. When
varnishing over sap or knots, apply the varnish directly to the wood and do not prime with shellac.
35
Incompatible Building Materials
9.2 Flooring, resilient
General information:
Resilient flooring is a popular flooring material that has a relatively firm surface but has “give” and
“bounce back” when compressive forces are removed. Common types of resilient flooring include
vinyl composition tile, vinyl tile and sheet, linoleum tile and sheet and rubber tile and sheet.
9.2.1 Resilient flooring/Concrete sub-base
Problem: Improper material selection can lead to premature failure of resilient flooring installed
over concrete slabs:
•
Moisture emissions from the slab can lead to adhesive and flooring failure.
•
Concrete sealers and curing compounds may not be compatible with adhesives used to secure
resilient flooring to the slab.
•
Adhesives: Some adhesives are not compatible with some types of resilient flooring and will
cause shadowing or inadequate bonding.
Reporting source: B.C. architect
Solution: Follow instructions from the resilient flooring manufacturer carefully and carefully ensure
that specifications for other areas of work (concrete slab placing and curing) are consistent with the
warranty requirements for the floor covering. Failure to do so may result in premature failure and
the voiding of warranties.
•
Moisture emissions from the slab: All concrete substrates must be fully cured and free of any
hydrostatic and/or moisture problems. The moisture vapour emission from a concrete slab must
not exceed 1.36 kg/92.9m2 (3 lbs. per 1,000 sq. ft.) per 24 hours, as measured by test method
ASTM F1869-98.
•
Concrete sealers and curing compounds: Concrete substrates must be clean and free of concrete
sealers and curing compounds, and any substance that may prevent or reduce adhesion.
•
Adhesives: Resilient flooring manufacturers have tested their products with adhesives and
provide strict directions on the compatible adhesives to use. Use only adhesives that are
specifically designed, recommended and guaranteed by either the resilient flooring
manufacturer and/or the adhesive manufacturer for the specified floor covering material. Check
with the flooring and adhesive manufacturers for the latest product recommendations and
warranty information.
9.2.2 Resilient flooring/Wood panel sub-floor
Problem: Certain wood panel underlays emit surfactants (surface-active contaminants) that can
cause discoloration of resilient flooring.
Reporting source: B.C. architect
36
Incompatible Building Materials
Solution: Verify with the resilient flooring manufacturer the types of wood panel sub-flooring that
will be compatible with their warranties. Although building codes permit the use of several kinds of
wood panel for sheathing and underlay, some resilient flooring manufacturers require wood
underlay to be underlayment-grade with a fully sanded face. Such manufacturers do not usually
accept particleboard, OSB, cement backerboards, glass mesh mortar units or acoustical cork. When
specifying resilient flooring, check with the manufacturer for suitable underlayment so that
warranties will be honoured.
Most resilient flooring manufacturers recommend specific adhesives, seam sealers and floor care
products that have been formulated and extensively tested for their products. In many cases,
warranties will be voided if unapproved products are used.
Specify wood underlayments recommended and guaranteed by either the wood underlayment
manufacturer and/or the floor-covering manufacturer. All wood underlayments must be
acclimatized and installed in strict accordance with the manufacturer’s written instructions.
9.2.3 Resilient flooring/Floor fills and toppings
Problem: Many products such as cellular concretes, resin-reinforced self-levelling cement
underlayments and gypsum-based products are recommended by their manufacturers for use as
floor fills or toppings. However, some resilient flooring manufacturers caution that
“all recommendations and guarantees regarding the suitability of these products and their
performance as underlayments (for resilient flooring) are the responsibility of the manufacturer
and installer of the underlayment system used.”
This warning is an indication that there have been performance problems when some types of
resilient flooring have been placed over floors that have been levelled or topped.
Reporting source: Literature search
Solution: The manufacturers of resilient flooring, adhesives and cement-based self-levelling and
patching products may not warranty their products when applied and installed over gypsum-based
self levelling underlayment and gypsum-based patching compounds. Before completing
specifications, consult with both the leveller/topping manufacturer and the resilient flooring
manufacturer to ensure compatibility and the honouring of warranties.
When self-levelling underlayments and patching products are required for the surface preparation
of substrates prior to the installation of floor covering materials, specify cement-based products.
9.2.4 Resilient flooring/Latex-backed rugs and mats
Problem: It is reported that use of latex-backed rugs or mats over resilient flooring can cause
discoloration of the resilient flooring. A typical example would be the use of a mat over the flooring
in front of a kitchen sink. The latex backing may cause permanent discoloration of the resilient
flooring.
Reporting source: B.C. construction management company
Solution: Before using any covering over resilient flooring, builders and homeowners should verify
with the flooring manufacturer that the proposed mat and the resilient flooring are compatible.
37
Incompatible Building Materials
Division 10–Specialties
No reports
Division 11–Equipment
No reports
Division 12–Furnishings
No reports
Division 13–Special construction
No reports
Division 14–Conveying systems
No reports
38
Incompatible Building Materials
Division 15–Mechanical
Other mechanical-related reports:
5.1.1 Copper tubing/Aggressive soils (page 19)
5.1.2 Copper pipe/Plumbing (page 20)
5.1.4 Metal strapping seismic restraint/Hot water heaters (page 21)
7.3.2 Sealants/Vent pipes (page 29)
15.1 High-temperature vent pipes/Combustion gas
Problem: Failures have been reported in high-temperature plastic vent pipe (HTPV) and fittings
that were installed between 1987 and 1993 for venting Class III mid-efficiency furnaces. The
failures include hairline cracking, splitting, and separation of joints that can result in leakage of
combustion products, including carbon monoxide, into the home.
The deterioration of the pipe is thought to result from acids resulting from the combustion process.
Horizontal pipe sections are at greater risk than vertical sections because condensate containing the
acid remains in contact with the inner surfaces for longer periods. The damage is progressive, causes
the pipes to become increasingly brittle and fragile, and it is not possible to predict when failure
will occur.
Reporting source: Literature search
Solution: Vent pipes serving mid-efficiency furnaces installed between 1987 and 1993 should be
inspected. Any defective pipe should be replaced. After 1993, the plastic pipe was reformulated to
avoid the deterioration problem.
39
Incompatible Building Materials
Division 16–Electrical
16.1.1 Smoke alarms/Halogen lighting
Problem: There are reports that some types of hard-wired, multi-station smoke alarms commonly
used in residential construction are prone to false alarms when they are wired in series with
receptacles or fixtures that include halogen lighting. The false alarm problem can occur with multistation smoke alarms that are low-voltage interconnect units–when one smoke detector in a circuit
goes into alarm, it sends a low-voltage signal (9VDC) to put the other alarms on the circuit into
alarm. The false alarms are caused by voltage fluctuations resulting from the transformers powering
the halogen lights.
Nuisance false alarms can result in homeowners temporarily disconnecting the smoke alarm, or in
some cases, removing the alarm, leaving no alarm protection in the case of fire.
Reporting source: Construction management firm
Solution: The best solution is to ensure smoke alarms do not share a circuit with other devices.
Otherwise, check with the manufacturer to ensure smoke alarms are compatible with proposed
wiring arrangements. This problem was reported for one particular type of smoke alarm. The
solution reported is the use of another model (by the same manufacturer) that operates by
maintaining a line voltage and is therefore less prone to voltage fluctuations in the circuit.
16.1.2 Electrical wiring/CPVC pipe
Problem: Certain types of wire and cable jacketing may contain “plasticizers” that are used to
make the plastic insulation softer and more flexible. When wiring with jackets that contain these
plasticizers are in constant contact with plastic components such as chlorinated polyvinyl chloride
(CPVC) pipe, the plasticizers may leach out and cause the pipe to soften. Occasional contact
during building construction (for example, dragging wires across CPVC pipe) does not seem
to transfer enough plasticizer to cause a problem.
Reporting source: B.C. architect
Solution: Wiring should be kept isolated from CPVC pipe and other plastic materials.
40
Incompatible Building Materials
Trend Analysis
The first effort at compiling examples of material incompatibility has generated 35 examples (in
addition, there are many other examples that have not been included because they were seen to be
inappropriate uses of materials or violation of well-known good practices). The analysis of the
examples that were included in this report (and others that were not included) results in some
general observations about particular areas of difficulty.
Education
Several examples were reported that involve dissimilar metals. While there will always be examples
of incompatibility that cannot be avoided–even the manufacturer has not foreseen certain
limitations–many incompatibilities are well documented but are either ignored or not recognized.
Therefore, it is likely that recurring metal incompatibilities demonstrate a need for ongoing training
or skills upgrading.
Sealants
Sealants are a group of materials with a fairly high number of reported incompatibilities. This is
likely due to the wide range of formulations and applications for such products. Because they are
often formulated for specific applications, problems or poor performance are bound to occur when
a sealant is used for an application for which it was not designed.The General Information section
for sealants will assist builder practitioners to make educated sealant selections. It would be helpful
for all stakeholders if sealant tubes had a simple label used by all manufacturers that indicated
product uses and limitations.
Builder awareness
Builder surveys provide insight into where the majority of building defects are occurring.
A 1992 survey made by the NAHB Research Centre determined that the most frequent reports
of callbacks were attributable to:
•
Paints/caulks/finishes
•
Flooring
•
Windows and skylights
•
Doors
•
Foundations and basements
•
Siding and trim
•
Structural sheathing
•
Wallboard
•
Foundation insulation and waterproofing
•
Framing
41
Incompatible Building Materials
A survey of the major housing defects reported to the Ontario Home Warranty Program in 1994
by homeowners listed, in order of frequency, the following:
•
Gypsum wallboard
•
Foundation wall
•
Window/door/skylight
•
Trim and moldings
•
Windows/skylights/skylight frames
Although there is no direct link between defects and incompatibilities, this information indicates
assemblies that require special vigilance, and a reminder to ensure known building material
incompatibilities are avoided as a possible source of failure in assemblies with a high history of
defects.
From time to time, new materials or building techniques enter the marketplace with the promise
of performance and cost-effectiveness. In some cases, unforeseen service conditions or circumstances
result in major difficulties. Exterior insulated finish systems (EIFS), composite sidings and
polybutelyne water piping are examples of materials or systems that did not perform as expected,
and indicate that product testing and building code development do not circumvent all possible
problems. Therefore, the designer and builder need to continually be educating themselves and
making careful choices based on experience and judgment.
Builders are renowned for job-site ingenuity and innovation. Using tools and materials in
unforeseen ways to ease effort may result in economies but may also result in unsafe work
conditions or practices that violate building science principles or code requirements. Care is
required when applying innovation, but as a minimum, job-site time savers should respect known
material incompatibilities.
Uses of materials
In some cases, incompatibility results from using materials outside their range of approved or tested
applications. For example, it was reported that contractor’s sheathing tape, designed for sealing
vapour/air barriers, is used for applications for which it may perform but performance has not been
tested or approved.
The Canadian Construction Materials Centre (CCMC) is one of the organizations that evaluates
new materials, products, systems and services for all types of construction. The results of the
product evaluations are published in the highly regarded CCMC Registry of product evaluations.
Published quarterly on the CCMC Web site (www.nrc.ca/ccmc/) and annually in print, the
Registry contains evaluation reports that include complete, illustrated descriptions of products,
instructions for use along with any restrictions and detailed test results. Each report also contains
an impartial technical opinion of how a product performs in relation to its planned use.
In the case of sheathing tape, the CCMC evaluations assess the performance of the tape with
specific sheathing and membrane materials. If the tape is used with other sheathing material or for
other applications, there is no guarantee of performance and in some cases, usage may be contrary
42
Incompatible Building Materials
to code requirements. For example, there are reports of both sheathing tape and duct tape being
used to seal duct joints in forced-air heating systems without clear indication that the tapes meet
the NBCC flame-spread requirements for such applications.
Although duct tape has many useful temporary uses on the job site, its effectiveness for permanent
applications is doubtful, and it is reported to have a very short performance effectiveness in
applications close to heat sources. It is essential to ensure that innovative uses of products do
not violate building code requirements.
Instruction labels
From the cases uncovered during the research for this project, it is obvious that some problems
encountered by builders result from a failure to read or respect product limitations noted on the
product packaging. For example, the rush to apply paint in unheated conditions as fall
temperatures decrease often ignores the temperature application ranges recommended on the
product.
While exceeding the product limits may get the project completed in time, it also brings a fairly
high likelihood of recalls later, often at higher cost than doing the work according to instructions
in the first place.
Trend summary
Building is a complex process that requires knowledge of a wide array of products and principles.
Education and continual skills upgrading is needed for building professionals to stay aware of the
limitations of both old and new products. It appears that many incompatibilities could be avoided
if:
1. Manufacturers could find a clearer, harmonized way to indicate product limitations on
product packaging. Sealants, for example, have numerous formulations and there are many
manufacturers. A standard label on each tube of sealant indicating best uses, appropriate
and inappropriate uses would help simplify product selection.
2. Building professionals need to read and understand product uses and limitations and make
product selections that will avoid incompatibility problems.
43
Incompatible Building Materials
Building Code Issues
There were two reports that pertained to the building code and product standard. These have been
passed to the appropriate agency for possible action.
44
Incompatible Building Materials
Appendix A: Research Sources
This list summarizes the groups, publications, associations, companies and organizations contacted
by telephone, e-mail or Web site review during the research stage of gathering cases of building
material incompatibilities.
Industry associations
Alberta Floor Covering Association
Alliance of Canadian Building Officials
Building Envelope Research Consortium
Building Owners and Managers Association
Canadian Association of Home and Property Inspectors
Canadian Home Builders’ Association
Canada Mortgage and Housing Association
Canadian Roofing Contractors Association
Canadian Wood Council
Construction Specifications Institute
Energy & Environmental Building Association
Forintek Canada Corp.
Greater Vancouver Home Builders Association
Homeowner Protection Office of British Columbia
Manufactured Housing Institute
National Association of Home Builders
National Association of Home Builders Research, ToolBase Hotline
Partnership for Advancing Technology in Housing (PATH)
Starline Windows
Architectural associations
Alberta Association of Architects
Architects’ Association of New Brunswick
Architectural Institute of British Columbia
Manitoba Association of Architects
Nova Scotia Association of Architects
Ontario Association of Architects
Ordre des architectes du Québec
Royal Architectural Institute of Canada
Saskatchewan Association of Architects
45
Incompatible Building Materials
Government and regulatory bodies
Canadian General Standards Board
Housing and Urban Development (HUD)
Institute for Research in Construction,
Canadian Construction Materials Centre
Occupational Safety and Health Administration
Public Works and Government Services Canada, National Master Specifications
Research and university
Australian Material Safety
Commonwealth Scientific and Industrial Research Organisation, Australia
Concordia University, Department of Building, Civil, and Environmental Engineering
Institute Of Materials, U.K.
Oakridge National Laboratory, Energy Sciences
Pennsylvania Housing Research Center
University of Illinois, Seitz Materials Research Laboratory
University of Maryland Materials Research Science and Engineering Center
University of Ottawa, Environmental Health and Safety Service
University of Pennsylvania, Materials Research Society
University of New Brunswick, Civil Engineering, Materials
University of New Orleans, Advanced Material Research Institute
University of Southern Mississippi, School Of Engineering Technology
University of Waterloo, Civil Engineering
University of Windsor
Publications
ASM Handbook Volume 11: Failure Analysis and Prevention, R.J. Shipley, W.T. Becker,
ASM International.
Building Materials: Dangerous Properties of Products in Masterformat Divisions 7 and 9, H. Leslie
Simmons, Richard J. Lewis, Sr., Wiley.
Construction Sealants and Adhesives, 3rd Edition, Julien R. Panek, John Phillip Cook, Wiley.
Durability by Design, National Association of Home Builders Research Centre, 2002.
Failure Mechanisms in Building Construction, David H. Nicastro, American Society of Civil
Engineers (ASCE Press), 1997.
Wall Moisture Problems In Alberta Dwellings, Technical Series 2000-112, CMHC
46
Incompatible Building Materials
Periodicals
AIA Architecture
Architectural Digest
Architectural Record
Architectural Journal
Architectural Record
Builder Magazine (NAHB)
Builder Online
Canadian Building Digest
Canadian Home Builder Magazine
Canadian House and Cottages
Fine Homebuilding
Hanley-Wood Publications
Homes and Cottages
Journal of Light Construction
McGraw Hill Construction (ENR, Sweets, Arch Record, etc)
Progressive Architecture
Professional Builder Professional Remodeler NAHB
This Old House
ToolBase E news
47
Incompatible Building Materials
Appendix B: Survey
INCOMPATIBLE BUILDING MATERIALS
In 2003, Canada Mortgage and Housing Corporation completed a report titled “Incompatible
Building Materials” to document cases of building material incompatibility reported by builders,
renovators, inspectors and architects. The report is intended to initiate shared learning so that
others can avoid problems.
The report is a start to the identification of building materials incompatibility. You can help by
adding your knowledge and experience to future editions of the report by completing and returning
the survey form below.
Typical documented examples of incompatibilities
Framing materials
Fasteners affected by cedar, redwood and treated wood products in wet locations
Wet materials: sealants, adhesives and coatings
Solvent-based sealants, adhesives and damp-proofing affecting polystyrene rigid insulation
Silicone sealant affecting paintability and recaulking
General
Metals affecting metals–dissimilar metals
Copper tubing affected by aggressive (acidic soils)
Your example
Your name: __________________ Tel: (
) ___________ Email: ____________________
Problem (symptoms, causes, conditions, time-frame etc.): _______________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
Solution (if there is one): ________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
Return to:
CMHC
Policy and Research Division
700 Montreal Road, Ottawa, ON
K1A 0P7
Att: Darrel R. Smith
Senior Researcher
48
email: [email protected]
tel: (613) 748-2348
fax: (613) 748-2402
Incompatible Building Materials
Acknowledgements
Canada Mortgage and Housing Corporation expresses its gratitude to the following organizations
and individuals who contributed to this project.
Advisory committee
Walter Burningham, W.E. Burningham & Associates
Don Johnston, Canadian Home Builders Association
Alphonse Caouette, Canadian Construction Materials Centre (CCMC):
Paul Morris and Jennifer O’Conner, Forintek Canada Corp.
Bob Switzer, Polygon Construction Management Ltd.
Skip Lennox, Glidden ICI Paints
John Straube, University of Waterloo
Chad Foreshew, Ontario New Home Warranty
Rick Bortolussi, City of Richmond/B.C. Building Officials Association:
Technical reviewers
Lyndon Mitchell, NRC, “Division 3–Concrete”
Sivan Parameswaran, NRC (retired), “Division 5–Metals”
Paul Morris, Forintek Canada Corp., “6.1.1”
Bruno Di Lenardo, Canadian Construction Materials Centre, IRC, “7.1 Envelope”
Joseph Borsellino, Patenaude JBK, “7.2 Roofing”
Jerome Klosowski, sealants expert, “7.3 Sealants”
Skip Lennox, Glidden ICI Paints, “9.1 Coatings”
Jean Claude Carisse, National Floor Covering Association, “9.2 Flooring, Resilient”
Alberta Floor Covering Association, “9.2 Flooring, Resilient”
Survey respondents
Henry Bakker
Kane Bentson
Gilles Bernard
Daryl Birtch
Bart Blainey
Rick Bortolussi
Tom Bowen
Eric Clough
Gerry Coming
Andy Cook
Luis de Miguel
Paul Denys
Ted Gilmour
Don Grant
Jim Greenshields
William Hadikin
Wayne Heath
Michael Hill
Karl Klatt
Ian Knight
Walter Kuch
Ben Levinson
Richard Lind
Dennis Looten
Thorien Maillot
Jack Mantyla
Ted Maxwell
Jim McCubbing
Robert Mearns
Bruce Miller
Hugh Miller
Jim Morrison
Greg Nelson
Myron Pasaluko
Murray Pound
Joe Ross
Kevin Sawlor
Andrew Skelton
John Slowski
Allen Smith
Darrel Smith
Bob Switzer
Tom Trestain
Bernardine Van der Meer
Victor Zukowski
Marshall Zwicker
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Visit our home page at www.cmhc.ca
23/06/05
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