Design Considerations

This section deals with roof system design considerations. Although every situation cannot be dealt with specifically, an overview of roof system components and their function is provided. Each component is discussed in general terms and the properties / capabilities are outlined relative to similar components having the same function. The intention is not to assess or directly compare specific products. Space has been provided for "RGC Accepted Materials" manufacturers (see Section 2.2) to provide technical product information. (See also Section 4.5, Section 5, and Section 6 for specific membrane information.)

The design authority is responsible for both the design of the roof system and the selection and specification of the various elements within the system, as they relate to the specific project. Many factors affect the life of a roof system and should be of concern to the owner and design authority.

Roof failures may occur as a result of:

• poor application or carelessness on the part of the roofing contractor
• selection of a roofing contractor unfamiliar with the products/system specified (usually based on price)
• poor work practices on the part of the general contractor or other subtrades
• inadequate or lack of inspection of the installation and conformance to specifications
• lack of representation and technical support from the membrane / material manufacturer
• incorrect selection of materials
• poor quality of materials

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Roof Classes