A cool roof reflects sunlight and releases the heat it absorbs, and a Los Angeles reroof may need to show that it does. Three questions settle the test: the share of roof replaced, the slope, and the climate zone of the address. Inside the City of Los Angeles a local rule adds to it.
The terms, one at a time
Three numbers describe a cool roof surface. Aged solar reflectance is how much sunlight it bounces back once weathered, from 0 to 1. Thermal emittance is how freely it releases absorbed heat. SRI blends the two into a single figure.
Products are listed in the CRRC directory, and the label on a package carries those values. Slope splits the rules in two: over 2:12 is steep, and 2:12 or flatter is low (LADWP, 2022).
The state tables, by zone and slope
Read the state table in this order: share replaced, slope, zone. The share comes first. Beyond 50 percent of a single-family roof, with an overlay counted as replacement, the test starts. At 50 percent or less, or for repairs, it does not (California Energy Commission, 2022 Standards).
Then the slope and the zone. A steep roof in zone 4 or zones 8 to 15 can pass with SRI 16 (aged reflectance 0.20, emittance 0.75). A low roof in zone 4 or zones 6 to 15 needs SRI 75 (0.63 and 0.75), and a separate insulation table offers a trade-off.
What the code accepts instead
A steep-slope house can skip the reflective test by another door. Ceiling insulation at R-38 works. A radiant barrier works too, provided spaced sheathing is not under it. R-2 continuous insulation above or below the deck also counts, and a fourth route exists in zones 2, 4, 9, 10, 12 and 14, where the attic has no ducts.
Solar panels exclude the area beneath them, and a roof of 25 pounds per square foot or heavier is excluded too. Tile profile and raised battens are talked about as exemptions, yet the 2022 and 2025 texts name neither (California Energy Commission).
The 2025 code and the City of Los Angeles
The 2025 Energy Code, effective 1 Jan 2026, carries the same reroof text. Executive Order N-29-25 sets aside part of that update when a house lost in the 2025 Los Angeles fires is rebuilt (California Energy Commission).
A residential cool roof rule of the City's own has been in full effect in Los Angeles since 1 Jan 2015, triggered once more than half the roof is replaced. Steep slopes need SRI 20 and low slopes SRI 78, and repairs or work on half or less are outside it (LADWP, 2022).
Climate zones across the county
The Energy Commission's list assigns the zone by ZIP code. Pasadena and Santa Clarita are zone 9, Norwalk is zone 8, and the ZIP codes of Malibu, Brentwood, Santa Monica, Long Beach and Torrance are zone 6. Palmdale and Lancaster are zone 14.
Inside Los Angeles proper, 113 ZIP areas split as zone 6 for 13, zone 8 for 21, zone 9 for 77 and zone 16 for 2. One county, four or five zones: hence the habit of reading the zone from the address.
What readers ask about cool roofs
How do climate zones split across the county?
Zone by zone, ZIP by ZIP. Pasadena sits in 9, Norwalk in 8, Malibu and Long Beach in 6 and Palmdale in 14, and the Energy Commission's list gives the zone for any ZIP code.
How do I look up a product's CRRC listing?
Find the product in the CRRC directory of tested products, then compare its aged reflectance, emittance and SRI with the target for your slope and zone. Many products carry the same values on their label.
What alternatives does the code accept?
Any one of four will do on a steep slope. Those are R-38 in the ceiling, R-2 continuous insulation at the deck, a radiant barrier kept off spaced sheathing, and a ductless attic where the zone is listed (California Energy Commission, 2022 Standards).