a small white modern house with a pool in the foreground, and California mountains in the background with palm trees

Cool roofs are becoming increasingly popular in energy-efficient and sustainable buildings. For many people, a heat-reflective roof is an excellent investment that can reduce cooling costs.

Many local, state and federal government entities have embraced cool roofs in green building standards, energy efficiency programs, and building codes. Undeniably, the state of California has been one of the pioneers in adopting cool roofs in warm climates here in the US. In fact, it is the only US state with energy efficiency standards that entail mandatory requirements for certified cool roofing provisions. 

However, it is worth noting that requirements for cool roofs differ by state or national climate zones in some cases. Therefore, be sure to refer to relevant climate zones to understand the needs in your area.

If you’re thinking of installing cool roofing in California, be warned that the guidelines in California’s Title 24 cool roof requirements can be a bit hard to navigate.

But don’t fret. As experts on California cool roof requirements, we can help you understand the guidelines and install a compliant cool roof for your property.

Keep reading to learn everything about California’s cool roof requirements. 

What Are Cool Roofs? 

Cool roofs are essentially roofing systems that extend greater solar reflectance and higher thermal emittance than conventionally-designed roofing products.

Generally, cool roofs come in white or some other cooler shade. But recently, that dynamic has changed with the introduction of cutting-edge cool roof products that can attain qualified levels of solar reflectivity even in rich, dark hues.

In addition, installing a cool roof in California can also improve the durability of your roof and diminish building cooling loads as well as the urban heat island effect.

Moreover, cool roofs can benefit both you and the environment by cutting down energy consumption. They will reduce your energy bill in addition to minimizing greenhouse gas emissions.

6 Basic Cool Roof Types 

If you wish to enjoy the countless benefits of cool roofs, or if your climate zone and the type of roof necessitates one, typically you have the following three options: 

  • Recover your property’s roof with new waterproofing that offers heat reflection
  • Retrofit the roof with heat-reflective materials 
  • Replace the roof altogether with cool roofing products

If your roof is not in excellent condition and is relatively old, we highly suggest replacement unless it qualifies for recovery or retrofit. 

Several commercial buildings have low-pitched or flat roofs. Such roofs often require cool roofing as they receive the most direct sunlight compared to other roof forms. Here are some of the most common types of cool roofs available in the market:

Green Roofs

An excellent option for low-sloped and flat roofs. Green cool roofs feature plant cover and even an entire cultivated garden.

Although it is costlier to install, we can’t overlook that it also provides several more benefits than other types of cool roofs.

A closeup of a green roof in an urban environment

It can turn your roof into an enjoyable space while helping you counteract urban heat island and qualify your property for environmental certifications. Restaurants, hotels, other service industry businesses can also use green cool roofs to attract guests. 

Single-Ply Membranes

Black, heat-absorbing materials are typically used in pre-fabricated roll-on roofing sheets. However, painting your roof with a reflective coating or replacing it with white sheets can make the roof much more energy-efficient.

Metal Roofs

Metal is a naturally reflective material. But there is no denying that it is a poor thermal emitter. Thus a metal roof on its own can’t be considered a cool roof. However, painting the metal surface with a reflective coat or a light, cool color can do the trick.

The top of a home with cool metal roofing is shown along with a chimney stack

Built-Up Roofs

You can upgrade your roof in numerous ways. One option is to replace the asphalt topcoat or gravel with reflective marble chips.

Likewise, you can also use reflective factory-applied coating or mineral granules. A built-up roof’s asphalt layer can easily be coated with either of these options. 

Spray Polyurethane Foam Roofs

This roof is cool by design. The material is white and requires a coating to protect it from UV damage and moisture. These coatings are highly reflective.

Workers retrofitting a home with a cool roof in the desert with spray foam polyurethane
Workers retrofitting a home with a polyurethane cool roof

Modified Bitumen Sheet Membranes Roofs

These are plastic or rubber roofs with a top layer of mineral granules and fabric reinforcements. They come with a cool roof pre-coating that’s factory applied. 

Cool Roof Requirements in California 

Every three years, the California Energy Commission updates Part 6 of California’s Title 24. However, cool roof requirements differ by region within the state. Therefore, you must consult and check with your local jurisdiction to determine which requirements are applicable. In addition, requirements for individual locales might be stricter than the ones discussed here. 

What Is Solar Reflectance Index (SRI)?

For those not aware, cool roof requirements in California are grounded on the SRI or solar reflectance index. Cool roofing materials are designated a particular SRI value ranging from 0 to 100.

The higher the SRI value, the cooler the material is likely to become in daylight. In contrast, a material with a lower SRI has a greater chance of turning hotter in sunlight. 

SRI for roofing materials is calculated using the aged thermal emittance and solar reflectance measurements of the asphalt gravel materials. As stated above, the values vary between 0 to 100. The measure is used to indicate how hot gravels are expected to become when exposed to direct sunlight.

  • The lower the value, the more likely the gravels become hot in the sun. 
  • On the contrary, roofing asphalt gravels with a greater SRI value will help cut down the cooling load on your property. 

Know Your Climate Zone

According to Building Energy Efficiency Standards Title 24, Part 6 (California), California is divided into sixteen climate zones. Therefore, you must be aware of your climate zone and get familiar with the particular cool roof requirements to be fulfilled before starting any cool roofing project.

Source: California Energy Commission 

Cool Roof Requirements for the City of Los Angeles 

According to California Energy Commission, the asphalt gravels for the city of Los Angeles should meet or exceed a solar reflectance index value of 16 for all reroof applications in commercial and residential buildings and even for new constructions. 

Cool Roof Requirements for Los Angeles 

Asphalt gravels must meet or exceed a solar reflectance index value of 20 for all reroof applications in commercial and residential buildings and even for new constructions for the unincorporated Los Angeles County regions. According to the Green Building Standards Code of Los Angeles County, this is also a compulsory condition.

Cool Roof Requirements in California 

Excluding overriding local guidelines, the remaining California state (including all other incorporated Los Angeles County regions) falls under the policies outlined in the state’s Building Energy Efficiency Standards Title 24, Part 6. Therefore, whether any rule applies or not is based on your property’s location relative to the sixteen California zones presented in the guideline.

There aren’t any cool roof requirements for climate zones 1 to 9 and 16, whereas in zones 10 to 15, asphalt gravels must reach or exceed a solar reflectance index value of 16 for all reroof applications (in which more than 50 percent of the roof is removed) and new construction applications.

The criteria apply to all commercial and residential properties. Moreover, in climate zones 10 to 15, mounting a cool roof with an SRI that meets, or is greater than 16, is one of three possibilities to exhibit code compliance.

Hence, cool roofs are deemed a ‘tradeoff’ option. In addition, asphalt gravels with an SRI value below 16 can be used in these regions if they’re installed in combination with an air space or a radiant barrier or where extra attic insulation supplements the shingle installation. 

Feel free to refer to the Building Energy Efficiency Standards Title 24, Part 6 to learn more about these alternative compliance paths. However, in most instances, contractors comply with the guidelines by installing a cool roof that meets or exceeds the SRI value of 16. 

Conclusion 

Whether adding finishing touches to a newly constructed property or embarking on a reroofing project, be sure to leverage California’s incentive programs for businesses and homeowners using cool roofing materials.

So, paint your roof white or install any style of cool roof to enjoy the multitude of benefits, including energy conservation, lower energy bills, reduced carbon footprint, and a more comfortable space for family members and employees alike.

Hopefully, this guide has provided you with a much clearer idea regarding California’s cool roofs.

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