Typical scope
- CRRC-rated membranes and coatings with the product listing your inspector will ask for
- Aged solar reflectance and thermal emittance values checked against the applicable requirement
- Insulation upgrades where the scope of work triggers them
- Documentation package for permit submittal and final inspection
- Reflective options across TPO, PVC, white EPDM, coatings and cap sheets
What a cool roof is
A cool roof reflects more sunlight and radiates more absorbed heat than a conventional one. Two numbers define it. Solar reflectance is the fraction of sunlight reflected rather than absorbed. Thermal emittance is how readily the surface radiates away the heat it did absorb. Both are measured when new and again after three years of weathering, the aged value is what codes reference, because every roof loses some reflectance to dirt and weathering.
How Title 24 applies
The California Building Energy Efficiency Standards, Title 24 Part 6, set prescriptive cool-roof requirements for re-roofing as well as new construction. For nonresidential low-slope roofs the prescriptive path commonly calls for an aged solar reflectance of about 0.63 and a thermal emittance of about 0.75, or an equivalent Solar Reflectance Index. Residential low-slope requirements differ, and some climate zones and some scopes of work are exempt or have alternative compliance paths.
The values above are a general orientation, not a code citation for your project. What actually applies depends on your climate zone, the building occupancy, and how much of the roof is being altered, a small repair and a full replacement are treated very differently. Confirm the requirement with your local building department before material is ordered, because the wrong product means a failed inspection and a second roof.
The CRRC listing
Compliance is demonstrated with a product rated by the Cool Roof Rating Council. The CRRC tests and publishes initial and aged reflectance and emittance for listed products, and that listing is what an inspector will want to see in the submittal. Ask the contractor for the CRRC listing of the specific product proposed, not just an assurance that it is white.
The side benefit
Beyond compliance, a reflective surface reduces peak surface temperature substantially, which cuts cooling load and, often more valuable, reduces the daily thermal movement that opens seams. A cooler membrane ages more slowly.