Title 24 reroof requirements decide what a new roof on a flat or low-slope house has to include: a reflective "cool roof" surface, added insulation, both or neither, depending on the roof's slope and your climate zone. As of November 2026, the rules are in the 2025 California Energy Code (Title 24, Part 6), which applies to permit applications filed on or after January 1, 2026.
Our Eichler roof replacement guide covers foam, membranes and the low-slope insulation numbers. This guide covers the rest: what counts as a reroof, how shallow gable roofs are treated, what each Bay Area climate zone requires, the exceptions worth asking about, product labels, and permit steps in the two cities whose reroof pages we could read, Cupertino and Menlo Park.
When a reroof triggers the Energy Code
Section 150.2(b)1I applies when the exterior surface of an existing roof is replaced, "including adding a new surface layer on top of the existing exterior surface," and more than 50 percent of the roof is being replaced. The code defines a roof recover as a new covering installed over a prepared existing one without removing it, and a roof replacement as tearing off the covering, repairing damaged substrate and installing a new one. Both fall under that language.
The California Energy Commission's 2025 compliance manual says the Energy Code applies to alterations but not to repairs, and that replacing a component the code regulates, such as a roof covering, is an alteration. One wording difference: the manual's worked example says cool roof rules are triggered when "50 percent or more" of the roof is replaced, while the Standards say "more than 50 percent." If your project is right at half, ask the building department which reading it applies.
Low-sloped or steep-sloped: the 2:12 line
The Energy Code defines a low-sloped roof as one with a rise of less than 2 in 12 and a steep-sloped roof as 2:12 or more. The line matters on houses with shallow gables. Cupertino's R1-e Eichler district allows roof slopes up to 3:12, and Palo Alto's two-story objective design standards call for roof pitches of 3:12 or less on two-story projects in mapped Eichler tracts. Under the Energy Code, a gable at 2:12 or 3:12 is a steep-sloped roof, which carries a much lower reflectance target than a low-sloped roof.
Houses with both kinds of roof must meet the low-slope rules on the low-slope areas and the steep-slope rules on the rest, or use the performance approach, according to Example 9-13 in the manual. Have your roofer measure each roof plane and write the slopes on the bid.
What each Bay Area climate zone requires
California has sixteen building climate zones. The CEC's ZIP code list places the ZIP codes below in these zones, but it also notes that a ZIP code can contain more than one climate region and that local jurisdictions may assign one zone to the whole ZIP code. Confirm your address with the CEC's climate zone search tool or your building department.
Climate Zone 3 (examples: 94025 Menlo Park, 94402 and 94403 San Mateo, 94070 San Carlos, 94131 San Francisco, 94611 and 94619 Oakland, 94546 Castro Valley, 94941 Mill Valley). The reroof section sets no prescriptive cool roof requirement for either slope and no added insulation for low-sloped roofs.
Climate Zone 4 (94301, 94303 and 94306 Palo Alto; 94022 Los Altos; 94040 and 94043 Mountain View; 94086 and 94087 Sunnyvale; 95014 Cupertino; 95051 Santa Clara; 95008 Campbell; 95032 Los Gatos; 95070 Saratoga; 95118, 95124 and 95125 San Jose). Low-sloped roofs need an aged solar reflectance of at least 0.63 and thermal emittance of 0.75, or an SRI of 75, plus R-14 continuous insulation or a U-0.039 assembly, with trade-offs and exceptions. Steep-sloped roofs need an aged solar reflectance of 0.20 and emittance of 0.75, or an SRI of 16.
Climate Zone 12 (94596 and 94597 Walnut Creek, 94518 Concord). The same low-slope and steep-slope rules as Zone 4.
Climate Zone 2 (94903 San Rafael). No cool roof requirement for either slope, but low-sloped roofs still need R-14 continuous insulation or U-0.039, with exceptions.
Section 10-106 also lets a city or county adopt stricter local energy standards, after it adopts a cost-effectiveness finding and the CEC finds the rules save energy. Ask your building department whether a local rule adds to these.
Exceptions worth asking about
For steep-sloped roofs, Exception 1 treats any of these as equivalent to the cool roof requirement:
a ceiling U-factor of 0.025 or less, or at least R-38 ceiling insulation;
a radiant barrier in the attic that meets Section 150.1(c)2;
in Climate Zones 2, 4, 9, 10, 12 and 14, no ducts in the attic;
R-2 or more continuous insulation above or below the roof deck.
The code doesn't say how the "no ducts in the attic" exception reads for a house with no attic at all, such as an exposed-beam ceiling, so ask the plan checker before you rely on it. For either slope, roof area covered by building-integrated solar panels is exempt from the reflectance rules, and so are roofs weighing at least 25 pounds per square foot.
For low-sloped insulation, our roof replacement guide covers the R-10, R-4 and tapered-insulation exceptions. Two more are worth asking about: in Climate Zones 1, 2, 4 and 8 through 10, an existing assembly of U-0.056 or less, or at least R-19 between the rafters in contact with the deck; and a reduction where thicker insulation would push the flashing at an existing door or window opening below what its manufacturer or a design professional allows. The performance approach, run in compliance software, is the alternative when the prescriptive path doesn't fit.
Products, labels and coatings
Section 110.8(i) requires a roofing product used to meet the reroof rules to have its thermal emittance and aged solar reflectance certified and labeled under Section 10-113, which names the Cool Roof Rating Council as the rating body. The packaging label must list the emittance and the initial and aged solar reflectance, or a CRRC Rapid Rating. A product without a rating is assigned default values of 0.10 reflectance and 0.75 emittance (0.08 for asphalt shingles), which won't meet a 0.20 or 0.63 target.
Liquid-applied coatings used as the top surface of a low-sloped roof must be applied across the entire roof at the coating maker's recommended dry mil thickness or coverage, and must meet the performance properties in Table 110.8-C or the listed ASTM standards. Their packaging must say they meet Section 110.8(i)4. Keep the labels and product listings for the inspector.
Paperwork and city permits
The manual says alterations that change the building envelope need a certificate of compliance (CF1R) submitted with the permit application. Its prescriptive alteration forms include the CF1R-ALT-01-E and CF1R-ALT-05-E, and the performance approach produces a CF1R-PRF-01-E.
The two city pages we read show how much local steps vary:
Cupertino. Its Instant Permits page, open only to licensed contractors with an online account, lists re-roofs for non-historic properties with no HOA, like-for-like work, "no Eichler," residential only, and says permit types it doesn't list need a Standard Building Permit. Ask the Building Division which path an Eichler re-roof takes. Its reroof and tear-off policy (revised February 2024) requires a tear-off inspection with dry rot already replaced, a nail inspection if new solid sheathing goes on, and no underlayment or roofing until inspections are approved. At final, flat roofs must have at least 1/4 inch per foot of slope with no ponding, product listings must be on site, the inspector may ask to verify a Class A fire rating, and smoke and carbon monoxide alarms must meet California Residential Code R314 and R315. Solar panels removed for the work need a separate permit to go back up.
Menlo Park. Its reroof worksheet (revised July 2026) asks for the existing and new roof's material, weight, layers, pitch and sheathing, whether Title 24 forms were submitted, whether a cool roof is required, and the roof classification. Inspections listed are tear-off, roof nailing, in-progress and final.
As of November 2026, two state rules also apply statewide. Health and Safety Code Section 13132.7 sets a minimum fire class for roof coverings, including when more than 50 percent of the roof area is replaced within one year: at least Class C in most areas, at least Class B in state responsibility areas outside moderate zones, and Class A in very high fire hazard severity zones unless the city has adopted the State Fire Marshal's model ordinance. Cities may require more, and the installer must give the owner a certification of the covering's class. Section 13113.7 holds the final sign-off on a permit over $1,000 until the required smoke alarms are State Fire Marshal listed; our home sale requirements guide covers that rule, and our wildfire hardening guide covers ember-resistant roofs and vents.
This is general information as of November 2026, not legal advice. Confirm your climate zone, permit path and any local energy rules with your city's building department, and use a licensed roofing contractor.
Frequently asked questions
Does Title 24 apply if I only patch my roof?
The reroof section applies when more than 50 percent of the roof is replaced (the manual's example says 50 percent or more), and the Energy Code doesn't apply to repairs. Your city may still require a permit for the patch, so ask the building department before work starts.
Is a 2:12 roof low-sloped under the Energy Code?
No. A low-sloped roof has a rise of less than 2:12; at 2:12 or more it's steep-sloped, with a lower reflectance target. Houses with both must meet each rule on its own roof area or use the performance approach.
Do I need a cool roof in Climate Zone 3?
Not under the 2025 reroof section, which sets cool roof requirements only in Climate Zones 4 and 6 through 15 for low-sloped roofs and 4 and 8 through 15 for steep-sloped roofs. Check whether your city has adopted a local energy rule under Section 10-106.
Does a roof recover count as a reroof?
Yes. The reroof section covers replacing the exterior surface, including adding a new layer on top of the existing one, when more than half the roof is involved.
Related reading
Eichler Roof Replacement: Foam, Membranes and Above-Deck Insulation
Flat Roof Drainage on Mid-Century Homes: Fascia, Gutters and Grading
Insulating an Exposed Beam Ceiling: Above the Deck, Edges and Walls
More guides on this topic: Owning & Renovating a Mid-Century Modern Home
Replacing a roof before you sell, or pricing one into a purchase? Call or text the Boyenga Team at Compass at (408) 373-1660 or (650) 383-8606, or contact the Boyenga Team to talk through the permit and timing.
