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Roofing Underlayment

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Peel-and-stick underlayment applied to the plywood roof deck during the installation of a standing seam metal roof.

“Tar paper” underlayment (asphalt-impregnated roofing felt) during the installation of an asphalt shingle roof.

Related Pages

1. General: “Roofing Underlayment Types” is a good, short, introductory article available on the InterNACHI website.

2. General: “The Use of Underlayment with Asphalt Shingles” explains why you use it. Available at the Canadian Asphalt Shingle Manufacturers’ Association website.

3. General: #15 and #30 Roofing Felt: “Weights and Measures of Underlayment for Roofing” is a good short overview of these materials (including an explanation of what that “#” symbol actually means. On the Atlas Roofing website.

4. Building Codes: “R905.1.1 Underlayment” from the 2018 International Residential Code. Available at the UpCodes website. For underlayment sections in the 2018 International Building Code, you have to look under the subsection for each specific roof covering, beginning with “Section 1507 Requirements for Roof Coverings“. Always check with your local authority to verify which code is in effect in your jurisdiction, and whether it has been amended.

5. Building Codes: “R905.1.2 Ice Barriers” from the 2018 International Residential Code. For ice barrier sections in the 2018 International Building Code, you have to look under the subsection for each specific type of roof covering, beginning with “Section 1507 Requirements for Roof Coverings“. Ice barrier sections are under the underlayment sections for the specific types. For example, for asphalt shingles: “1507.2.7 Ice Barrier“. Always check with your local authority to verify which code is in effect in your jurisdiction, and whether it has been amended.

6. Technical: “Grace Ice & Water Shield HT” is a product sheet worth taking a look at for information on this very popular underlayment. Includes product description, guidelines for use, and installation procedure. Available at GCP Applied Technologies.

7. Technical: “Installation of Asphalt Shingles on Low-Slope Roofs” is a technical bulletin from the Canadian Asphalt Shingle Manufacturers’ Association. Provides guidelines for installing shingles on roofs with slopes between 2/12 and 4/12.

8. Manufacturers: See this list of roofing underlayment manufacturers.