Title 24 Cool Roof Rules for San Diego Homeowners

California’s current energy standards took effect on 1 January 2026 and apply to permits filed on or after that date. They do not apply to every roof. Residential requirements depend on your climate zone and whether the surface is low-slope or steep-slope, and roof areas covered by solar panels are exempt. A small repair usually does not trigger them at all. Your permit is what settles it for your address.

Rancho Roofing is a licensed C-39 contractor in Encinitas, CSLB #1153860. This page explains what the rules actually require, which projects trigger them, and the paperwork that comes with compliance.

The short version is worth knowing before you read further. This is not a blanket rule, and much of what gets said about it locally is broader than the code itself.

What changed, and when?

The 2025 standards took effect on 1 January 2026 for permits filed on or after that date.

The Cool Roof Rating Council describes the 2025 Building Energy Efficiency Standards, Title 24 Part 6. They set requirements for thermal emittance, three-year aged reflectance, and Solar Reflectance Index, in new construction and re-roofing.

LegalClarity’s May 2026 summary confirms the effective date applies to permit applications filed on or after 1 January 2026. RoofVista’s April 2026 guide adds the corollary: projects permitted under the earlier cycle stay under the prior standards for the duration of that permit.

So the date that matters is when the permit was filed, not when the work happens.

Does it apply to my house?

That depends on your climate zone, your slope, and whether panels cover the area.

This is the part most local advice gets wrong by generalising. US Made Supply’s May 2026 summary sets out the actual scope. Nonresidential low-slope cool roofs are required in all sixteen climate zones. Residential requirements are narrower: single-family steep-slope re-roofs in zones 4 and 8 to 15, and low-slope re-roofs in zones 4 and 6 to 15.

Two exemptions matter and are often missed. Heavy roofs of 25 pounds per square foot or more are exempt, which covers a lot of tile. And roof areas covered by photovoltaic or solar-thermal panels are exempt entirely.

Coastal San Diego is generally climate zone 7. Under those lists that puts a low-slope re-roof inside the requirement and a single-family steep-slope re-roof outside it. Confirm your own zone rather than taking that from any article, including this one, and let the permit settle it. The California Energy Commission publishes the zone maps.

What does the standard actually require?

Aged reflectance of 0.63 and thermal emittance of 0.75 on low-slope, an SRI of roughly 75.

RoofVista’s April 2026 summary of the 2025 update gives those low-slope figures. Steep-slope roofs in the hottest zones, particularly 10 to 14 covering the Central Valley and Inland Empire, carry higher aged reflectance under the prescriptive path.

Solar Reflectance Index combines two things into one number: how much sunlight a surface reflects rather than absorbing, and how efficiently it radiates absorbed heat back to the sky. It runs roughly 0 to 100 and higher is cooler.

One detail worth understanding. US Made Supply notes the prescriptive values are aged values, measured after three years of field exposure or computed by protocol. Real roofs collect dirt and weathering that reduce reflectance. A product’s out-of-the-box number is not the number the code uses.

What triggers compliance, and what does not?

A full tear-off does. A small repair usually does not.

RoofVista’s April 2026 guide is specific. Any replacement involving a full tear-off plus deck repair beyond minor localised patches triggers full compliance, whether or not the roof was previously cool-rated. Recover projects generally trigger it when they affect more than half the roof area.

At the other end, like-for-like repair of a small leak or a limited section below roughly 300 square feet typically does not trigger compliance at all. The same source notes the threshold was lowered in the 2025 update, so more tear-off and deck-repair work now counts as an alteration than did before.

Compliance is documented on three forms. The CF1R is prepared before the permit and sets the pathway and the product. The CF2R is prepared after installation by the installing contractor, verifying that what went on matches what was specified. RoofVista notes officials are checking both more rigorously at inspection now, with fewer retroactive accommodations.

What if a cool-rated surface is wrong for the house?

There are alternative paths, and they cost a few hundred dollars to document.

RoofVista’s April 2026 guide describes an insulation trade-off path. Common trade-offs include adding R-5 to R-10 of attic insulation above the prescriptive minimum, a radiant barrier under the deck, above-deck continuous insulation, or improved attic ventilation.

The calculation runs through approved state software and is documented on the CF1R. Expect $200 to $800 in consultant fees for that path, on the same source’s figures.

US Made Supply also notes that a liquid-applied coating can be a route to compliance where the product is rated for it. More on those in which coating chemistry suits which failure, and we handle the compliance paperwork with compliance handled as part of the job rather than as an afterthought.

Does a cool roof have to be white?

No. Compliance is measured on reflectance and emittance, not color, and rated products exist across a broad range of colors. The rating is what matters, so the question to ask is whether a specific product is listed, not what shade it is.

Do solar panels really exempt the roof under them?

US Made Supply’s May 2026 summary lists roof areas covered by photovoltaic or solar-thermal panels as exempt. That is the area under the array specifically, not the whole roof, so the uncovered portions are treated normally.

Who is responsible for the compliance paperwork?

The CF1R sits with the designer, contractor, or a Title 24 consultant before the permit. The CF2R is the installing contractor’s, after installation. Ask which of those your contractor handles before signing, because a missing form shows up at inspection.

Does a repair need a cool-rated product?

Usually not. RoofVista’s guidance is that like-for-like repair of a small leak or a limited section below roughly 300 square feet typically does not trigger compliance. The trigger is scope, so a genuine repair stays outside it.