New CT Roofing Requirements for New and Reroofing
Chapter 9 - Roof Assemblies
(Amd) R90S.1.1 Underlayment. Underlayment for asphalt shingles, clay and concrete tile, metal roof shingles, mineral-surfaced roll roofing, slate and slate type shingles, wood shingles, wood shakes and metal roof panels shall conform to the applicable standards listed in this chapter.
Underlayment materials required to comply with ASTM D 226, D 1970, D 4869 and D 6757 shall bear a label indicating compliance to the standard designation and, if applicable, type classification indicated in Table R905.1.1(1}. A minimum 4-inch-wide strip of self-adhering polymer-modified bitumen membrane complying with ASTM D 1970, installed in accordance with the manufacturer's instructions for the deck
material, shall be applied over all joints in the roof decking. Underlayment shall be applied over the entire roof and over the 4-inchwide membrane strips and shall be applied in accordance with Table R905.1.1(2}. Underlayment shall be attached in accordance with Table R90S.1.1(3}.
Underlayment materials required to comply with ASTM D 226, D 1970, D 4869 and D 6757 shall bear a label indicating compliance to the standard designation and, if applicable, type classification indicated in Table R905.1.1(1}. A minimum 4-inch-wide strip of self-adhering polymer-modified bitumen membrane complying with ASTM D 1970, installed in accordance with the manufacturer's instructions for the deck
material, shall be applied over all joints in the roof decking. Underlayment shall be applied over the entire roof and over the 4-inchwide membrane strips and shall be applied in accordance with Table R905.1.1(2}. Underlayment shall be attached in accordance with Table R90S.1.1(3}.
Exceptions:
- As an alternative, self-adhering polymer-modified bitumen underlayment complying with ASTM D 1970 installed in accordance with both the underlayment manufacturer's and roof covering manufacturer's instructions for the deck material, roof ventilation configuration and climate exposure for the roof covering to be installed, shall be permitted.
- The 4-inch-wide strips of self-adhering polymer-modified-bitumen membrane are not required for
roofs sheathed with lumber having a nominal width of less than 3 feet.