California Title 24 Cool-Roof Rules for LA Homeowners

Guide · Codes · Updated June 2026 · Affordable Roofing Los Angeles

What a Cool Roof Actually Is

A cool roof reflects more sunlight and sheds more heat than a standard roof, so the surface stays cooler and less of that heat works its way into your attic and living space. Two numbers define it. Solar reflectance is the share of sunlight the roof bounces back instead of absorbing, on a scale from 0 to 1. Thermal emittance is how efficiently the surface radiates the heat it does absorb back out into the air, also 0 to 1. California combines those two into a single rating called the Solar Reflectance Index, or SRI, which is the number building inspectors actually look at.

Higher SRI means a cooler roof. A plain dark asphalt shingle might sit around an SRI of 10 to 15. A bright white coating can land above 80. In a city like Los Angeles, where summer roof-surface temperatures in the Valley can climb past 150 degrees, the difference between a roof that absorbs that heat and one that throws it back off is something you feel in your upstairs bedrooms and on your August electric bill.

It helps to separate the two physical effects. Reflectance is about not absorbing the heat in the first place, and emittance is about getting rid of whatever heat does get absorbed. A roof can be good at one and weak at the other. Bare metal, for example, can reflect reasonably well but has low emittance, so it holds heat. A good cool roof scores high on both, which is why the SRI combines them into one number. When you compare products, the SRI is the apples-to-apples figure to ask for, and any cool-rated material will list it on its spec sheet.

How Title 24 Treats Low-Slope vs. Steep-Slope Roofs

California's Title 24 energy code separates roofs into two categories, and the rules are different for each. Low-slope roofs (the flat or nearly flat roofs common on mid-century homes, additions, and commercial buildings) face the strictest cool-roof requirements. When you reroof a low-slope roof statewide, the new surface generally has to use a cool-rated material that meets minimum reflectance and emittance values. That is why you see so many white TPO and white-coated flat roofs across LA now.

Steep-slope roofs (your standard pitched shingle or tile roof) get more flexible treatment. The state minimums are lower, and tile and certain shingle products often qualify without a dramatic change in appearance. If you are weighing a flat-roof reroof, our breakdown of flat roof options in Los Angeles walks through which membranes meet the cool-roof rule and which need a coating on top. For the flat-roof service itself, see flat roof repair and replacement.

The City of LA Steep-Slope SRI Rule

On top of the statewide Title 24 baseline, the City of Los Angeles adopted its own cool-roof ordinance that pushes steep-slope roofs further. In practice, steep-slope roofs in the City of LA are expected to use materials rated around SRI 20 when you reroof. That sounds restrictive, but the manufacturers have caught up. Plenty of asphalt shingles now carry a cool-rated line that hits the number, and most concrete and clay tile already qualifies because of how tile sheds heat.

What matters for you as a homeowner is that the rule is enforced through the permit. When a licensed contractor pulls your reroof permit, the inspector checks that the material you installed carries the right rating. Skip the permit and you skip that check, which becomes a problem later. We cover that whole process in our LA roof permit guide.

One practical note: the ordinance generally applies when you reroof, not when you simply repair a small section. A spot repair that replaces a handful of tiles or patches a leak usually does not trigger the cool-roof requirement. But once you cross into a full reroof or replace a large enough area, the new surface has to meet the standard. If you are in a bordering city like Glendale rather than the City of LA proper, the exact steep-slope number can differ, which is one more reason to work with a roofer who knows the local code. Our Glendale roofing team handles those jurisdiction differences day to day.

Exemptions and Where the Rules Bend

The cool-roof requirements are not absolute. Title 24 includes prescriptive paths and performance paths, which means a roof that does not meet the cool-roof number on its own can still comply if the whole building's energy performance is modeled to hit the target another way (more attic insulation or added radiant barrier, for example). There are also allowances tied to roof area, slope, and existing assemblies.

Historic districts are the other big exception. In an HPOZ or on a designated historic property in neighborhoods like Pasadena, Highland Park, or Los Feliz, the appearance of the roof is protected, and a bright white surface that clashes with the home's character may not be allowed. In those cases the cool-roof rule is balanced against historic preservation, and the path forward usually involves a tile or shingle product that meets the rating while keeping the right look. If you own a tile roof in one of these areas, our Pasadena roofing and Highland Park roofing pages cover the local specifics. We do not guess on exemptions. We confirm the right path with the building department before we order material.

Do Cool Roofs Actually Save Money in LA?

For most of Los Angeles County, yes, and the savings are bigger the farther inland you go. A home in Woodland Hills, Sherman Oaks, or Glendale that bakes all summer sees more benefit from a reflective roof than a home in Santa Monica sitting under the marine layer most mornings. The cooler your roof runs, the less your air conditioner cycles, and the less heat soaks into an attic that is already fighting to stay ventilated.

The savings are real but not magical. A cool roof typically trims summer cooling costs by a meaningful margin rather than cutting your bill in half. It pairs best with good attic ventilation and insulation, which together keep that reflected-heat advantage from leaking back into the house. If your upstairs rooms are uncomfortable and your roof is dark and aging, a cool reroof plus ventilation work is one of the more sensible upgrades you can make in this climate. Our Woodland Hills and Sherman Oaks crews see the inland heat difference firsthand.

There is a comfort payoff that does not show up on the utility bill, too. A cooler attic means a cooler second floor, which is where most older LA homes get unbearable in summer. It also takes some strain off your roofing material itself: less heat soaking into the assembly means the underlayment and the deck run cooler and age a little slower. So the cool roof you install partly to satisfy Title 24 ends up doing three jobs at once, lowering cooling costs, making the house livable upstairs, and extending the life of the roof. The benefit is smallest right on the coast, where the marine layer already keeps roofs cool, and largest in the inland Valley heat.

Your Cool-Roof Material Options

You have a cool-rated version of almost every roof type. Here is how the common LA choices stack up.

If your flat roof is sound but dark and tired, a cool-roof coating is often the smartest move. It meets the reflectance requirement, extends the life of the membrane underneath, and costs a fraction of a full tear-off. For pitched roofs, a cool shingle or qualifying tile keeps you compliant without changing how the house looks from the street.

Permits, Inspection, and Getting It Right

Any reroof that triggers Title 24 also triggers a permit, and the licensed contractor pulls it, not you. That permit is what ties the cool-roof rule to an actual inspection. The inspector verifies the material rating, the underlayment, and the installation before the job is signed off. That paper trail protects your insurance coverage and your home's resale value down the line.

Affordable Roofing Los Angeles has handled LA's cool-roof rules since 2013. We are licensed (CSLB C-39) and insured, we pull the permit, and we match you with a cool-rated material that fits your home, your neighborhood, and the code. You can always verify any roofer's license at cslb.ca.gov before you sign. If you want eyes on your roof first, book a roof inspection or call us at (213) 770-4744, and if it is time for a full reroof, our roof replacement page covers what to expect.