Title 24 of California’s energy code contains the state’s building code regulations and standards to ensure newly constructed buildings are energy efficient. These regulations are updated every three years. The latest revision, published in 2022, went into effect on January 1, 2023.
An essential element of these new regulations refers to energy-efficient roofing materials, also called “cool roofs.” Learn about California roofing laws, the definition of a cool roof, and how to ensure your home or building meets cool roof requirements in California.
What is a Cool Roof?
A cool roof is an industry shorthand term to describe residential or commercial roofing materials designed to reflect sunlight as efficiently as possible.
A properly designed, California roof program-compliant cool roof absorbs less heat than a traditionally designed asphalt shingle roof during hot, sunny days. These designs reduce the heat penetrating through the roof into the house, causing the interior temperature to be less affected by outside temperatures.
Cool roofs use architectural shingles manufactured from modern, long-lasting materials and elements that minimize heat absorption, such as solar-reflecting granules.
What is a Title 24 Compliant Roof?
Roofing in California is Title 24 compliant when it meets the state’s cool roof energy efficiency standards as outlined in the California Energy Code, Title 24, Part 6. These standards depend on two essential factors: the roof’s SRI score and California’s cool roofing climate zones.
One of the primary factors used to measure a roof’s ability to reflect heat and meet state compliance is the Solar Reflectance Index (SRI), defined by the ASTM E1980-01 standard.
The roof’s materials are assigned an SRI score ranging from 0 to 100. The higher the score, the more efficiently they reflect sunlight and the more heat they prevent from entering the building. For example, Title 24 roof shingles are roofing materials designed to meet the state’s minimum SRI requirements for a specific climate zone.
California Roofing Climate Zones
According to the 2022 edition of the Building Energy Efficiency Standards, California is divided into 16 climate zones, each with different requirements to meet Title 24 compliance.
The California residential roofing codes define a minimum SRI score for newly built single-family residential buildings. The minimum score depends on the climate zone and whether the roof is low-sloped or steep-sloped. If the roof pitch angle is less than 9.5°, it is low-sloped. If equal or higher, it is steep-sloped.
For example, a single-family residential building with a low-sloped roof in climate zones 13 and 15 need roofing materials with an SRI of 75 to be Title 24-compliant.
Which Buildings Must Meet Title 24 Requirements?
According to the Cool Roof Rating Council website, California Title 24 new roof requirements apply to numerous building categories. Each combination of category and climate zone has different minimum SRI requirements.
- All newly-built non-residential buildings with low-sloped roofs: Minimum SRI 75
- Re-roofing projects on existing non-residential buildings with low-sloped roofs: Minimum SRI 75 if the project replaces or recoats over 50% or more than 2,000 square feet of the roof area, whichever is lower.
Hotel and Motel Guest Rooms
- Newly-built hotel and motel guest rooms with steep-sloped roofs:
- Zones 2, 4-16: Minimum SRI 23
- Zones 2-15: Minimum SRI 16, except in zones with a higher minimum SRI
- Newly-built hotel and motel guest rooms with low-sloped roofs: Minimum SRI 64 in zones 9, 10, 11, and 13-15
Single-Family Residential Buildings
- Newly-built single-family residential buildings with steep-sloped roofs: Minimum SRI 16
- Newly-built single-family residential buildings with low-sloped roofs: Minimum SRI 75
- Re-roofing projects on existing single-family residences with steep-sloped roofs: Minimum SRI 16
- Re-roofing projects on existing single-family residences with low-sloped roofs: Minimum SRI 75
Multi-Family Residential Buildings
- Newly-built multi-family residential buildings with steep-sloped roofs: Minimum SRI 16
- Newly-built multi-family residential buildings with low-sloped roofs: Minimum SRI 75
- Additions of more than 700 square feet to multi-family residential buildings: Depends on the roof’s specifications, per Section 170.2(a)
- Alterations to a low-sloped roof of a multi-family residential building: Minimum SRI of 75 if the project modifies more than 50% or 2,000 square feet of the roof area, whichever is lower
- Alterations to a steep-sloped roof of a multi-family residential building: Minimum SRI of 16 if the project modifies more than 50% or 2,000 square feet of the roof area, whichever is lower
What Are the Benefits of a Title 24 Compliant Roof?
Buildings with Title 24-compliant cool roofs can reflect solar heat more efficiently than standard or traditionally built roofing materials. The benefits offered by this type of roofing are the result of solar reflection and thermal emittance.
How Solar Reflection and Thermal Emittance Work
Cool roofs are more reflective, meaning they have a superior solar reflection to traditional roofs. The higher the solar reflection, the more sunlight and solar radiation the roof bounces away, such as infrared and ultraviolet rays. Consequently, roofs with high solar reflection also block more of the sun’s heat from entering the building.
Cool roofs also offer increased thermal emittance, meaning the roof’s materials let interior heat transfer back outside more effectively. In contrast, a low thermal emittance roof, such as the type used in colder states, is better at trapping and retaining heat inside.
Energy Benefits of Cool Roofs
In California, roofs with both a high solar reflection and thermal emittance are necessary to meet Title 24 compliance and offer homeowners numerous benefits.
Installing a cool roof helps reduce energy waste by easing the load on air conditioning systems and maintaining the interior temperature at optimal levels. This can significantly reduce utility bills.
Trust AJ Reyes Roofing for Your Roofing Project
The best way to ensure your home or building’s roof complies with the latest edition of the California Energy Code is to contact a professional roofing company. At AJ Reyes Roofing, we have the resources, top-quality materials, and expertise necessary to understand California legislation and build, repair, or alter roofs that meet the state’s requirements.
We offer various Title 24-compliant roofing materials and services to ensure your home or building is up to code while preserving its beauty and architectural quality. Contact us today for a quote.