Cool Roofs in Los Angeles: Energy Savings and Title 24 Requirements
Cool roofs cut LA cooling costs by 10-30%. Learn about Title 24 requirements, reflective materials, and rebate programs for homeowners.
A standard dark roof in Los Angeles can reach 150-170 degrees on a summer afternoon. A cool roof on the same home might hit 100-110 degrees. That 50-60 degree difference at the surface translates directly to lower attic temperatures, less strain on your air conditioning, and real savings on your energy bill.
Cool roofs aren’t a single product. They’re a category of roofing systems designed to reflect more sunlight and absorb less heat than conventional materials.
Is a cool roof required when you reroof in Los Angeles?
Inside the City of Los Angeles, yes, once you replace more than half of a home’s roof. The city’s Green Building Code requires roofing rated for 3-year aged solar reflectance and thermal emittance (or the matching Solar Reflectance Index), so the product on a roof replacement has to meet the minimums below. Repairs, replacing half the roof or less, and reroofs where solar is being installed are exempt.
| Roof on a low-rise home | 3-year aged solar reflectance | Thermal emittance | Or aged SRI |
|---|---|---|---|
| Low-slope (2:12 pitch or less) | 0.65 | 0.85 | 78 |
| Pitched (steeper than 2:12) | 0.25 | 0.85 | 20 |
These are the values in Los Angeles Municipal Code section 99.04.106.5 (Ordinance 187208, PDF), as the Cool Roof Rating Council summarizes them. High-rise residential buildings use the same reflectance and SRI values with an emittance of 0.75.
The full list of exceptions in the same ordinance:
- a roof repair, as the California Energy Code defines one
- replacing 50% or less of the total roof area
- a roof replacement where solar systems are being installed
- an addition with less than 500 square feet of new roof, or less than 50% of the total roof area, whichever is greater
- a roof with thermal mass over the membrane, green roofs included, weighing at least 25 pounds per square foot
The city asks more than the state on every value: 0.25 against 0.20 on a pitched roof, 0.65 against 0.63 on a flat one, and 0.85 emittance against 0.75 (the state numbers are in Title 24 and Your Roof, below). The city’s table also has no climate-zone column. The same minimums apply in Venice and San Pedro (Climate Zone 6) and in Sunland-Tujunga (Climate Zone 16), where the state’s reroof rule does not cover pitched roofs at all. And the city’s exceptions include no swap for attic insulation or a radiant barrier, which the state rule allows on pitched roofs.
Check the aged number, not the brochure number
The reflectance and SRI values in the table are 3-year aged values: what the surface still reflects after three years of weathering, as listed for each rated product in the Cool Roof Rating Council (CRRC) directory. A new surface reflects more, so a product’s initial number can look compliant while its aged number falls short.
When a new product has no aged rating yet, the code lets you calculate one with the CALGreen formula (as the CRRC prints it): aged reflectance = 0.2 + β × (initial reflectance - 0.2), where β is 0.65 for a coating applied on the roof and 0.70 for other products. Worked through for the city’s minimums:
- A flat-roof coating needs an initial reflectance of about 0.90 to reach 0.65 aged. A white coating sold at 0.85 initial calculates to about 0.62 and falls short.
- A factory-made flat-roof product, such as a membrane, needs about 0.85 initial.
- A pitched-roof shingle or tile needs an initial reflectance a little over 0.27 to reach 0.25 aged.
Outside the City of Los Angeles
The rule that counts is the one of the building department that issues your permit. Burbank, Glendale, Pasadena, Santa Monica and Beverly Hills run their own departments, and unincorporated areas such as East Los Angeles and Altadena are permitted by the county (how roof permits work in LA).
On a single-family home anywhere in California, the state Energy Code (PDF summary by the CRRC) applies when more than 50% of the roof is replaced, with the minimums in Title 24 and Your Roof, below. Its pitched-roof rule covers only Climate Zones 4 and 8 to 15, and its low-slope rule zones 4 and 6 to 15; the Energy Commission’s climate zone tool and ZIP code table give your zone.
A pitched roof can also meet the state rule without a cool product when the attic has R-38 ceiling insulation, a qualifying radiant barrier, no ducts in the attic (in zones 2, 4, 9, 10, 12 and 14), or at least R-2 continuous insulation at the roof deck.
What Makes a Roof “Cool”
Two properties define a cool roof:
- Solar reflectance measures how much sunlight the roof bounces back. Higher is cooler. A white membrane might reflect 70-80% of solar energy. A dark asphalt shingle reflects only 5-15%.
- Thermal emittance measures how well the roof radiates absorbed heat back into the air. Most roofing materials have high emittance naturally, but solar reflectance is where the big differences show up.
The combination of these two properties gives you the Solar Reflectance Index (SRI). California’s Title 24 energy code uses SRI and aged solar reflectance values to determine compliance.
Title 24 and Your Roof
California’s Title 24 Building Energy Efficiency Standards apply to all new construction and most reroofing projects. The requirements vary by climate zone, and the City of Los Angeles spans Climate Zone 6 (the coast from Pacific Palisades and Venice to San Pedro), Climate Zone 8 (parts of South LA), Climate Zone 9 (central LA and the Valley) and Climate Zone 16 (Sunland-Tujunga).
For steep-slope roofs (2:12 pitch or greater), Title 24 requires a minimum aged solar reflectance of 0.20 and thermal emittance of 0.75. For low-slope (flat) roofs, the requirements are higher: aged solar reflectance of 0.63 and thermal emittance of 0.75.
What this means in practice: if you’re replacing a flat roof in LA, you almost certainly need a cool roof system to pass inspection. For pitched roofs, many standard materials meet the minimums, but higher-performing cool options can exceed code and deliver greater savings.
Cool Roof Material Options
Reflective Coatings
Elastomeric or acrylic coatings applied over an existing roof surface. They’re white or light-colored and can boost reflectance from 10% to 70%+. Cost runs $1.50-$3.50 per square foot for material and application. Coatings work well on flat and low-slope roofs and can extend the life of an aging membrane by 10-15 years.
The prices on this page are estimates. Your final price is the one in your written proposal.
Single-Ply Cool Membranes
White TPO and PVC membranes are inherently cool. They reflect 70-80% of solar radiation out of the box. These are the standard choice for commercial flat roofs and work well on residential flat sections. Installed cost runs $6-$12 per square foot.
Cool-Rated Shingles and Tiles
Manufacturers now produce asphalt shingles and concrete tiles with special pigments that reflect infrared radiation even in darker colors. A “cool black” shingle can reflect 25-40% of solar energy compared to 5-15% for a standard black shingle. These products let you get better thermal performance without going to a white or light roof.
Metal Roofing
Light-colored or pre-finished metal panels with cool pigment coatings reflect 50-70% of solar energy. Metal’s natural thermal emittance is also high. A cool-rated metal roof is one of the top performers for energy efficiency on steep-slope homes.
Energy Savings in Los Angeles
The savings depend on your home, insulation levels, and AC usage. But studies from the Lawrence Berkeley National Laboratory and the California Energy Commission put the range at:
- 10-30% reduction in cooling energy for homes switching from dark to cool roofing
- 2-5 degree drop in indoor temperature during peak summer hours, even before the AC kicks in
- Attic temperature reduction of 20-40 degrees, which extends the life of insulation, ductwork, and stored items
For a home in the San Fernando Valley where summer AC runs nearly nonstop for four to five months, the annual savings can reach $200-$600 depending on the home’s size and efficiency. Over a 20-year roof lifespan, that adds up.
Rebates and Incentive Programs
The Los Angeles Department of Water and Power (LADWP) has historically offered cool roof rebates, though program availability changes year to year. Check the LADWP and SoCalGas rebate portals for current offerings. Some programs have offered $0.20-$0.30 per square foot for qualifying cool roof installations.
Federal energy efficiency tax credits may also apply. A roofing contractor familiar with LA’s requirements can point you to current incentive programs.
Frequently Asked Questions
Does the cool roof rule apply if I’m getting solar panels?
Not in the City of Los Angeles: the city’s code lists “roof replacement where solar systems are being installed” as an exception to its cool roof requirement. The wording points to a reroof done together with a solar installation, not a roof that may get panels some day, so confirm the exception with the city when you apply for the permit.
The state Energy Code’s own solar exception is narrower: it excuses only the roof area covered by building-integrated solar panels, so the rest of a new roof still has to meet its minimums. Los Angeles County and other cities can add their own rules, so confirm with the building department that issues your permit. If panels are planned, read why it often makes sense to replace your roof before solar panels go on.
How do I find a roofing product that meets the Los Angeles cool roof rule?
Search the Cool Roof Rating Council’s Rated Roof Products Directory with its “Minimum Radiative Properties” search and enter the city’s minimums for your roof: 0.65 aged reflectance and 0.85 emittance for a low-slope roof, 0.25 and 0.85 for a pitched one.
Ask your roofer to name the exact product and its CRRC listing in the written proposal, so you can check it against the directory before work starts. Rebate questions go to LADWP, which runs the city’s consumer rebate program, not to the rating council.
Is a Cool Roof Worth It?
If you’re reroofing anyway, the cost premium for cool materials is modest. Cool-rated shingles cost roughly the same as standard shingles. A white TPO membrane costs the same as a dark one. The biggest premium comes with cool coatings on existing roofs, but even there, the payback period is typically 3-7 years based on energy savings alone.
For flat roofs, the answer is simple: Title 24 likely requires it, and the energy savings are significant. For steep-slope roofs, the upfront cost difference is small and the long-term return is positive in a climate like LA’s.
Your roof absorbs more sun than any other part of your home. Making it work with you instead of against you is one of the most straightforward energy upgrades available. Call Best LA Roofing at (818) 491-7862 to discuss cool roofing options for your next project.