BETHESDA, M.D. – Final hearings for the 2012 International Green Construction Code (IGCC) conducted last month yielded a number of advances for energy efficient and sustainable thermal envelopes, such as the inclusion of a straightforward approach to minimum thermal requirements for roof and wall systems. In addition, the new code extends the minimum thermal requirements to all low-slope roof replacements involving above-deck insulation.
“Our association is impressed that for the first time, a national energy code makes specific and clear requirements on the thermal performance of a retrofit roof,” said Jared Blum, President of the Polyisocyanurate Insulation Manufacturers Association (PIMA). “Increasing insulation levels to the IECC minimum when replacing the roof offers a tremendous opportunity to significantly accelerate efficiency and save money. Insulation, through its consistent and enduring performance, remains one of the most important components in a reroofing project when it comes to reducing energy costs and carbon footprint.”
Specific roof thermal values
The minimum thermal requirements will be the same as originally envisioned in the IECC 2012 code. However, the benefit here is that the language has been clarified to avoid potential confusion as to whether or not replacement roofs require compliance. Specifically, roof R-values will be calculated by reducing the current International Energy Conservation Code (IECC) roof U-values by 10%, which will yield a minimum above-deck roof R-value ranging from R-22.2 in U.S. Climate Zone 1 to R-33.3 in U.S. Climate Zone 6. This provides a single mathematical approach to establishing R-value, and it allows organizations like PIMA to publish R-value tables and design guides to assist building designers in complying with the new code.
Minimum thermal values for low-slope roof replacements
Language has been added to the Existing Buildings chapter of the code to require low-slope roof replacements involving above-deck insulation to meet the minimum thermal requirements of the current International Energy Conservation Code. Although the R-values will be slightly lower than the new construction minimums discussed previously, they will provide a reasonable and uniform thermal standard for the most common form of commercial reroofing. And for situations involving low roof clearances that make it difficult to add more roof insulation, the new language includes an exception for roofs with limited flashing heights or other restrictions.
In addition to these key advances, several other roofing-related provisions of the IGCC are noteworthy:
• Previous restrictions on the use of prescriptive R-value standards were effectively eliminated from the code, which will assure that roofing and siding projects regardless of size can use simple and straightforward R-value standards in lieu of more complicated energy calculations.
• In addition, several proposals added to the materials sections of the code are likely to stimulate new material recycling opportunities in the roofing industry.
The International Codes Council will publish the first edition of the IGCC in the spring of 2012, and it is expected that many state and local governments will quickly adopt the IGCC as the primary benchmark for “green” construction standards and practices. As soon as the IGCC is published, PIMA will offer on its website a roof and wall design guide to complement the code and serve as an easy reference for building professionals designing to the code.
View All News