IMPORTANT NOTES
Building Codes
Installers need to be aware of building code requirements in the geographic areas where they are installing, and how the codes relate to the instructions given in this manual and by the siding manufacturer. The requirements of local building codes must always be observed, because they represent the legal requirements for an installation in a given jurisdiction. However, local codes are based on the national model building codes. Model codes themselves do not have the force of law until they are adopted by a state or local jurisdiction. In the United States, the primary source of model codes is the International Code Council, which publishes the International Building Code (IBC), International Residential Code (IRC), and International Energy Conservation Code (IECC). In Canada, the primary model code is the National Building Code (NBC), published by the National Research
Council of Canada.
Most of the model building codes, and thus the local codes based on them, recognize that the product manufacturer usually knows how its product should be installed in order to provide best performance. Therefore, most building codes reference the manufacturer’s instructions and state that the product must be installed according to the code and the manufacturer’s instructions. However, any specific requirement in a local code will usually override any provision of the manufacturer’s instructions, especially if the local requirement is more restrictive. Therefore, vinyl siding installations must always conform to local building codes, but the local code may also require that the installation conform to the siding manufacturer’s instructions.
The codes provide the greatest recognition to products that have been certified to a recognized standard by an approved quality control agency. In fact, current editions of the IBC and IRC model codes require: vinyl siding to be certified to ASTM D3679; polypropylene siding be certified to ASTM
D7254; insulated siding be certified to ASTM D7793; and all to be verified by an approved quality control agency. As relevant editions of the model codes are adopted by local jurisdictions, code officials will want to verify that the siding is properly certified (which can usually be determined by identifying the VSI certified product label on the box—see page 1) and that the installation conforms to the manufacturer’s instructions. Always be sure that the instructions are available on the job site for an inspector to review.
This manual is not a building code and it is not a substitute for the manufacturer’s instructions. However, it has been developed by referencing the provisions of the model building codes, the requirements of ASTM D4756, and generally accepted installation practices within the vinyl siding industry.
This manual therefore reflects the most common installation requirements that apply to the vast majority of vinyl siding products. Use this manual to understand how vinyl siding and soffit should generally be installed, but be prepared to comply with any differing provisions of local codes and the manufacturer’s instructions for a specific product.
Installing for Wind Load Resistance
Vinyl siding is remarkably resistant to high wind, given its light weight and relatively simple installation. But in order for it to perform to its potential, it must first be properly selected, and then properly installed.
All certified vinyl siding is tested for wind load resistance and must meet certain minimum requirements. This testing results in a “standard wind load design pressure rating,” or the maximum wind
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