Cool Roofs in California: Title 24 Compliance Guide

If you are building, renovating, or replacing a roof in California, Title 24 will shape the choice. Title 24 is the state’s Building Energy Efficiency Standards, and the cool roof provisions inside it determine which roofing products and assemblies are legal for your project. The standards have tightened steadily since the 2008 cycle and now apply broadly to both residential and commercial construction. This guide explains what a cool roof is, what Title 24 actually requires, where it applies, and how to specify a compliant roof without overpaying for credentials you do not need.

What “Cool Roof” Actually Means

A cool roof reflects more sunlight and emits more absorbed heat than a conventional roof, lowering surface temperature, attic temperature, and cooling demand. Two measured properties define cool roof performance:

• Solar Reflectance (SR): The fraction of solar energy the roof reflects back to the sky, on a scale from 0 to 1. A bright white TPO typically scores around 0.75 to 0.85.
• Thermal Emittance (TE): The fraction of absorbed heat the roof re-radiates rather than retaining, also on a scale from 0 to 1. Most modern roofing materials score above 0.85 here.
• Solar Reflectance Index (SRI): A composite metric combining SR and TE on a scale where a standard black surface scores 0 and a standard white surface scores 100. Title 24 uses both individual values and SRI thresholds in different contexts.

The Cool Roof Rating Council (CRRC) tests and certifies products to standard methods. Title 24 references CRRC-rated values when determining compliance.

What Title 24 Requires for Cool Roofs

Title 24 cool roof requirements vary by climate zone, roof slope, and building type. California is divided into 16 climate zones; the Bay Area covers zones 2, 3, 4, and parts of 12. Requirements have tightened in each update cycle (2013, 2016, 2019, 2022).

Low-Slope Roofs (Less Than 2:12)

Low-slope roofs face the strictest cool roof requirements because they receive direct overhead sun and contribute heavily to cooling loads.

• Nonresidential and high-rise residential: minimum 3-year aged Solar Reflectance of 0.63 and Thermal Emittance of 0.75, or aged SRI of 75
• Low-rise residential additions and replacements: slightly less stringent but still significantly above conventional dark roofs
• Most TPO white membranes meet these requirements out of the box; many PVC membranes do as well

Steep-Slope Roofs (2:12 and Steeper)

Steep-slope cool roof requirements are less restrictive because the sun strikes these roofs at oblique angles for much of the day.

• Most California climate zones do not require cool roof on steep-slope residential, though some specific zones do
• When required, typical thresholds are aged Solar Reflectance of 0.20 and Thermal Emittance of 0.75, or aged SRI of 16
• Lighter-color asphalt shingles, light tile, and most metal roofs can meet these thresholds with proper product selection

Climate Zone Variation

Title 24 climate zones reflect local conditions. Cool roof requirements are most stringent in hot inland zones (Sacramento, Central Valley) and slightly less stringent in cooler coastal zones. Bay Area projects span multiple zones; your contractor and architect should reference the specific zone that applies to your address.

Which Roofing Materials Meet Title 24

Many roofing products meet Title 24 cool roof requirements out of the box, particularly for low-slope work. For steep-slope work, the universe is broader because the thresholds are lower.

Low-Slope Materials That Comply

• White TPO and PVC membranes: Standard products from major manufacturers easily exceed Title 24 thresholds
• Reflective coatings on modified bitumen or built-up roofs: Silicone, acrylic, or aluminum coatings can bring older or darker roofs into compliance
• White EPDM: Less common in California but compliant

Steep-Slope Materials That Comply

• Light-colored architectural asphalt shingles: Many manufacturers offer cool roof-rated lines; verify with product literature and CRRC listings
• Light-colored concrete and clay tile: Naturally reflective in lighter shades
• Standing seam metal with reflective coatings: Galvalume, light-color painted finishes, and specifically-rated cool roof products
• Synthetic composite shingles: Available in cool roof-rated formulations

For specifics on each material category, our TPO roofing, shingle roofing, tile roofing, and metal roofing pages cover product options.

When Title 24 Applies and When It Doesn’t

Cool roof requirements apply broadly but not universally. Common triggers include:

• New construction: Always subject to current Title 24 standards
• Roof replacement: Generally subject when replacing more than a defined percentage of the roof area (typically 50 percent within 12 months)
• Substantial additions: New roofed area on additions is subject
• Re-roof over existing: Subject in most cases, with limited exemptions

Common exemptions include very small repairs, certain agricultural buildings, and specific historic or aesthetic-protected properties. Your local building department applies the current Title 24 cycle and any local amendments to your specific project.

The Real-World Benefits Beyond Compliance

Title 24 cool roof requirements are not just a regulatory hurdle. They deliver measurable benefits to property owners over the life of the roof:

• Lower cooling loads: Less air conditioning demand during summer afternoons, reducing energy bills
• Extended roof life: Lower surface temperatures slow membrane and shingle aging
• Reduced urban heat island effect: Particularly meaningful in dense urban areas
• HVAC equipment longevity: Less cooling work extends compressor and fan service life
• Compatibility with rooftop solar: Cooler rooftop ambient improves PV panel efficiency

For homeowners weighing color and material choices, the cool roof option often pays back over the life of the system through reduced operating costs and extended roof life.

How to Specify a Title 24-Compliant Roof

Getting compliance right is straightforward when you build it into the specification from the start:

• Identify your project’s climate zone using the California Energy Commission map
• Determine whether the roof is low-slope or steep-slope by measured pitch
• Pull the specific aged SR, TE, and SRI thresholds that apply
• Specify products with CRRC listings that meet or exceed those thresholds
• Keep documentation in the project file for permit application and final inspection
• Coordinate with your contractor on the manufacturer installation requirements that support the rated performance

For broader replacement planning, see our roof replacement service page. For a deeper look at how regional climate affects roofing choices in California, our post on Class A wildfire-resistant roofing covers the fire side of the same material conversation.

Frequently Asked Questions

Does Title 24 apply to my residential roof replacement?

Generally yes, if you are replacing more than 50 percent of the roof area within a 12-month period. Smaller repairs are typically exempt. Your local building department applies current Title 24 requirements to permit applications and final inspections.

Can I install a dark-colored roof in California?

On steep-slope residential roofs in many climate zones, yes. On low-slope nonresidential and most commercial roofs, no, unless you use a darker membrane with a reflective coating on top to meet the SR and TE thresholds. Product selection is more constrained for low-slope work.

What’s the difference between aged and initial Solar Reflectance values?

Initial values measure brand-new product reflectance. Aged values measure performance after 3 years of weathering. Title 24 uses aged values because that is what the roof will deliver over its service life. Manufacturers list both on CRRC product reports.

Does a cool roof help in foggy coastal Bay Area cities?

Less than in inland heat zones, but still measurably. Cool roofs deliver value anywhere cooling loads matter, and modern Bay Area homes with air conditioning benefit even in coastal microclimates. The savings are larger in Concord and Walnut Creek than in San Francisco or Daly City.

Will a cool roof affect my home insurance?

Not directly. However, cool roof products are often paired with Class A fire ratings and impact resistance ratings that can affect premiums or insurability, particularly in fire-prone zones. Your insurance agent can confirm specifics.

How do I prove Title 24 compliance to my building inspector?

The CRRC product listing for each specified roofing material, the manufacturer’s installation specifications, and the contractor’s written assembly documentation together prove compliance. Your contractor should provide this paperwork as part of the permit submittal and final inspection package.