Title 24 cool roof rules for a San Jose re-roof, explained

What the cool-roof rule requires

Part 6 of Title 24, California's energy code, sets minimum solar reflectance and thermal emittance values for roofing on most permitted re-roofs. In plain terms, the roof has to reflect a share of the sun and shed the heat it does absorb. Only products rated by the Cool Roof Rating Council count, and the rating is printed on the product literature and listed in the council's database.

San Jose's reroof code references are the California Residential Code chapter 9, the Building Code chapter 15 and the Title 24 energy code cool-roof standards, and reroof permits go through SJPermits.org.

When it applies to your roof

The trigger is the permit. San Jose requires a reroof permit when 25 percent or more of the roof is replaced in any 12-month period; smaller repairs are not permitted and not covered. Full cool-roof compliance is triggered when more than 50 percent of the roof is replaced within 12 months, which describes almost every whole-house re-roof.

Repairs, a few squares of shingle or a recoat of a sound roof, generally do not trigger it. If you are close to either threshold, ask before the work starts, because the permit decides the paperwork.

Choosing a compliant color

Most shingle manufacturers make cool-rated lines in lighter grays, tans and weathered woods, and many concrete tile and metal colors carry ratings too. Picking from the rated color deck is the simplest route: the permit application lists the product and its rating, the inspector checks the label, and nothing else is needed.

White single-ply membranes and white foam coatings on flat roofs comply easily, which is one reason they dominate low-slope re-roofs. Our roof replacement scopes list the rated product and color on the permit.

If you want a dark roof anyway

A dark charcoal or black shingle usually does not meet the prescriptive values. You can still use it through the performance trade-off path, where a certified energy consultant shows that the house meets the energy budget in other ways, such as extra attic insulation, better ductwork or a radiant barrier. One California code guide puts that consulting at $500 to $1,500, and it adds a step to the permit.

It is a legitimate route, not a loophole. It just needs to be decided before the shingles are ordered, not at the inspection.

How strictly San Jose checks it

Title 24 is statewide, but enforcement happens at the local building department. San Jose, Santa Clara and Sunnyvale require compliance documentation with a moderate level of review. Cupertino, Mountain View and Palo Alto review it more strictly, often asking for product specification sheets and checking labels on site. Since we work on both sides of those lines, we assemble the full documentation up front either way.

Cool roofs and comfort

The rule exists because San Jose summers are long and sunny, and a reflective roof keeps attics and upstairs rooms cooler. Reflective metal finishes can reflect up to 70 percent of solar energy. Pair a cool roof with balanced attic ventilation and the difference upstairs is noticeable on an August afternoon.