Cool roof installation means putting a reflective covering on a reroof so it meets the energy tests that apply. Only the top surface is judged. The layers below it, underlayment, flashing and deck, are planned exactly as they would be for any other replacement.
What the test looks at
A cool roof is measured by two numbers: how much sunlight the aged surface reflects, and how readily it gives off heat. Products are tested and labeled by CRRC, and the label is how a covering is shown to meet a rule.
SRI, the solar reflectance index, is an alternative single number that combines both.
The state test for a reroof
Start with the share of roof being replaced. Under the state energy code, work that goes past 50 percent of a single-family roof brings the cool roof test into play. An overlay is treated as replacement for this purpose, and anything at 50 percent or under stays outside it (California Energy Commission, 2022 Standards).
The figures depend on slope and zone. Zone 4 and zones 6 through 15 cover the low-slope case: SRI 75 is one route, and the other is 0.63 reflectance after aging plus 0.75 emittance. The steep-slope case is zone 4 and zones 8 through 15, with 0.20 and 0.75 or SRI 16. Reroof text carries over into the 2025 Energy Code (California Energy Commission), effective 1 Jan 2026.
What a cool roof installation includes
- A check of which test applies to the address and the share of roof replaced
- A covering whose CRRC label meets the values for your slope and zone
- Underlayment, flashing and deck work scoped as for any replacement
- Documentation the building department can read at inspection
- A note of any exception the house qualifies for
- The permit and inspection for the address
When the cool roof test is likely to come up
- A full reroof of a single-family house
- A reroof that overlays an existing covering
- A low-slope section being replaced on a house
- A reroof in the City of Los Angeles that passes half the roof
The City of Los Angeles adds its own rule
Homes in the City of Los Angeles have faced a cool roof rule since 1 Jan 2015, triggered once more than half of the roof's area is replaced. Its values come from LADWP, 2022: a steep slope needs SRI 20 (aged reflectance 0.25, emittance 0.85), and a low slope needs SRI 78 (0.65 and 0.85).
Repairs, partial jobs of 50 percent or less, and roofs carrying solar sit outside it. A separate City of Los Angeles provision requires the whole roof to meet current code when more than half is reroofed within one year.
Exceptions the code allows
Steep-slope houses have four ways around the reflective test. One is R-38 ceiling insulation. Another is R-2 continuous insulation at the deck. A third is a radiant barrier placed anywhere except over spaced sheathing. The fourth applies only in zones 2, 4, 9, 10, 12 and 14, where the attic must have no ducts.
Two blanket exclusions also exist: roof area under solar panels, and roofing heavier than 25 pounds per square foot. The code does not treat tile profile, raised battens or an air space as exceptions (California Energy Commission, 2022 Standards).
Questions about cool roofs
At what point does a reroof have to be cool under the state code?
The test applies on a single-family house once the replaced share passes 50 percent. An overlay is part of that total. Anything at 50 percent or less is exempt (California Energy Commission, 2022 Standards).
Is the City of Los Angeles cool roof rule the same in every climate zone?
The City writes its values by slope and not by zone: SRI 20 steep, SRI 78 low (LADWP, 2022). What triggers it is reroofing more than half of the area.
Which cool options exist for tile, shingle and flat roofs?
Each of the three has CRRC-labeled products. Tile and shingle are judged against the steep-slope values, flat roofs against the low-slope values. The label tells you which products clear them.
Do inland zones such as 9 and 14 face the cool roof test?
Yes. Both zones are among those the state steep-slope and low-slope tests cover. Zones 9 and 14 are also among the zones where having no ducts in the attic qualifies a steep-slope roof for an exception (California Energy Commission, 2022 Standards).
How can I look up a product's CRRC listing?
CRRC keeps a product directory. Search for the product by name or ID, then compare its aged reflectance and emittance with the values for your slope and zone. We can read the label against the rule for your address.