Title 24 Cool Roof Rules for Rosemead Reroofs

When does the energy code apply to a reroof?

Title 24, Part 6 is the California Energy Code. It covers more than new construction: alterations to existing homes, including reroofs, fall under it too. The cool-roof part applies when a reroof replaces 50% or more of the roof area. On some low-slope roofs, replacing more than 2,000 square feet also triggers it.

Routine repairs do not. Replacing a few shingles, a vent boot or a section of flashing is a repair, not a reroof. A partial replacement of one slope may or may not cross the line depending on its share of the total area, which is one reason the quote should state the roof's total squares and the squares being replaced.

What numbers must a Climate Zone 9 roof meet?

Rosemead and most of the San Gabriel Valley are Climate Zone 9. Coastal Los Angeles and Orange County fall in Zones 6 to 8, and the western Inland Empire is Zone 10, so a roofer working across the region has to check the zone for every address.

Aged reflectance is the value measured after a product has weathered outdoors, not the brighter number it shows new. Products have to be rated by the Cool Roof Rating Council (CRRC) and carry its label, which is what the inspector looks for. For comparison, ordinary dark asphalt shingles typically age to a solar reflectance of only 0.05 to 0.15.

Which roofs are exempt from the cool-roof rule?

The code lists several exceptions. The ones that come up most on sloped residential roofs are these:

• Heavy roofs: coverings weighing 25 lb/ft² or more, which includes most clay and concrete tile.
• Attic insulation: a ceiling insulated to R-38 or better.
• Radiant barrier: an attic radiant barrier meeting the code's specifications.
• No attic ducts: homes with no heating or cooling ducts in the attic.
• Solar arrays: the area under photovoltaic panels.

Exceptions have conditions, and the building department applies them. Upgrading insulation through attic insulation work is one route some owners take when they strongly prefer a dark roof. Confirm the exact path with the city before you commit to a color.

What changed for reroofs under the 2025 Energy Code?

California updates its Energy Code every three years. The 2025 edition took effect on January 1, 2026, and the edition that governs a job follows the date its permit application is filed. For a steep-slope home in Climate Zone 9, the headline numbers did not move: 0.20 aged reflectance and 0.75 emittance, or an SRI of 16. Several details around them did change.

• A new equivalent path: R-2 or greater continuous insulation above or below the roof deck now counts alongside R-38 ceiling insulation and a qualifying radiant barrier.
• The no-ducts exception still lists Climate Zone 9, so a home with its ducts inside conditioned space, or with ductless wall units, may qualify.
• Unrated products are penalized: a shingle with no CRRC rating must assume a default aged reflectance of 0.08, which fails the 0.20 target.
• Packaging labels must list the emittance plus both the initial and the 3-year aged reflectance, and that label is what the inspector reads on site.
• Liquid-applied coatings carry added product requirements beyond the CRRC rating, so a coating chosen for a flat section needs its data sheet checked against the code.

Cool roof shingles: the colors still on the table

A cool-rated shingle is not necessarily white. Manufacturers use reflective granules that bounce back more infrared light while still looking gray, tan, brown or even fairly dark. The 0.20 steep-slope target is modest, so many mid-tone colors qualify. The very darkest charcoal and black shingles usually do not.

When you choose, ask to see the CRRC aged rating for the exact color, not just the product line. Two colors in the same line can rate very differently. We put the product, color and rating into the written quote so there is no surprise at inspection.

Cool shingle or an exception: weighing the trade-offs

Most owners have four realistic ways to comply, and each one carries a cost beyond the roofing itself.

Our view: on most Rosemead ranch homes, a mid-tone cool shingle is the simplest path, and the money it saves is better spent on deck repair and ventilation. When an owner wants a near-black roof, R-38 insulation beats hunting for a dark product that barely passes, because the insulation keeps paying back every summer. On board-deck houses that need new plywood anyway, radiant-barrier sheathing is worth pricing, since it solves the spaced-sheathing problem in the same step.

Low-slope roofs, membranes and coatings

The 0.63 aged reflectance target for low-slope roofs effectively means a white or very light surface. On garages, additions and patio rooms, that usually means a white single-ply membrane or a reflective coating over a sound membrane. Our roof coating options explain which surfaces can be coated and which must be replaced first.

How we handle Title 24 on Rosemead reroofs

On every replacement quote for roofing in Rosemead, we confirm the climate zone, check whether the job crosses the 50% line, and look for an exception before talking color. Many of the post-war homes we work on have heating and cooling ducts in the attic and modest insulation, so the duct and insulation exceptions often do not apply as the house stands.

When the rule applies, we name a CRRC-rated product and color in the quote, keep the labeled packaging on site for the inspector, and pull the permit so the inspection is on record. The process is the same in El Monte and the other Zone 9 cities around us, though each city's building division has the final word on its own forms.

From quote to final inspection, step by step

1. Confirm the climate zone for the address with the Energy Commission's zone lookup, which works by ZIP code.
2. Measure the total roof area and the area being replaced, so the 50% line is a number rather than a guess.
3. Test each exception against the attic as it stands: insulation depth, duct location and sheathing type.
4. Choose the product and color, and write its CRRC product ID and aged rating into the quote.
5. File the permit with whatever energy compliance paperwork the building division asks for.
6. Keep labeled bundle wrappers or packaging on site until the inspector signs off the final.

Rebates and the next step

LADWP's cool-roof rebate is limited to LADWP electric customers in the parts of the City of Los Angeles it serves. Rosemead and most San Gabriel Valley cities are Southern California Edison territory, so check current SCE and Energy Upgrade California offerings directly before you count on any incentive.

If you are planning a reroof and want the code question settled before you pick a color, call (725) 745-8803 or request a quote. We will tell you whether the rule applies to your roof, which exceptions might, and which rated colors fit your house.