Examining Building Code Requirements<\/strong><\/h4>\n\n\n\nAccording to the National Roofing Contractors Association (NRCA), adequate slope can be achieved by sloping the structural framing or deck or by designing a tapered insulation system to accommodate water drainage. A combination of the above in conjunction with the use of roof drains, scuppers and gutters may be necessary to provide adequate drainage when reroofing.<\/p>\n\n\n\n
Chapters 11 and 15 of the International Building Code (IBC) contain the requirements for determining roof drainage. When tapered systems are the specified method for improving drainage, attention should also be paid to the International Energy Consideration Code\u2019s (IECC) requirements for the opaque building thermal envelope. The IECC establishes minimum insulation requirements for commercial building roof systems with insulation entirely above the roof deck (IEAD). In application, tapered roof insulation systems contribute to design solutions that meet the energy efficiency requirements outlined in the IECC.<\/p>\n\n\n\n
That said, up to and including the IECC 2018 edition, tapered roof insulation\u2019s contribution to meeting minimum energy efficiency requirements had only been addressed in a vague manner, leaving much up to interpretation. But with the publication of the IECC 2021 edition, the requirements for calculating the R-value of tapered roof insulation systems are clear.<\/p>\n\n\n\n
Section<\/em> C402.2.1.1, tapered, above-deck insulation based on thickness,<\/em> says where used as a component of a roof\/ceiling assembly R-value calculation, the sloped roof insulation R-value contribution to that calculation shall use the average thickness in inches (mm) along with the material R-value-per-inch (per-mm) solely for R-value compliance as prescribed in Section 402.1.3.<\/em> According to Section<\/em> C402.2.1.2, minimum thickness, lowest point,<\/em> the minimum thickness of above-deck roof insulation at its lowest point, gutter edge, roof drain or scupper, shall not be less than 1 inch (25 mm).<\/p>\n\n\n\nWith these clarifying changes, building owners can more easily take advantage of the added energy performance of tapered insulation.<\/p>\n\n\n\n