Roof replacement in the Bay Area: what it costs

Cool roof: replacing more than 50 percent of a steep roof (a pitch of 2:12 or more) in climate zones 4 and 8 to 15 calls for a roof with an aged solar reflectance of at least 0.20 and a thermal emittance of at least 0.75, or an SRI of at least 16. Exceptions include R-38 ceiling insulation, an attic radiant barrier, no attic ducts in zones 2, 4, 9, 10, 12 and 14, R-2 insulation above the deck, and roofs of 25 pounds per square foot or more.

Climate zones in the Energy Commission ZIP table: 94110 in San Francisco, 94611 in Oakland, 94702 in Berkeley and 94538 in Fremont are zone 3. 95112 in San Jose and 94086 in Sunnyvale are zone 4. 94520 in Concord, 94596 in Walnut Creek and 94550 in Livermore are zone 12. 95404 in Santa Rosa and 94558 in Napa are zone 2. The steep roof rule above lists zones 4 and 8 to 15.

Low-slope roofs have their own criteria in zones 4 and 6 to 15. A house with both kinds of roof meets both under the prescriptive approach. Replacing a wood shake roof with asphalt shingles counts as an alteration, not a repair.

A roof replacement removes the existing layers down to the roof deck. A new layer over the old one is not allowed if the old roof is water soaked or deteriorated, if it is slate, clay, cement or asbestos-cement tile, or if it already has two or more layers.

Outside fire hazard zones, a roof where more than 50 percent is replaced within one year needs at least a Class C fire rating. Inside a Fire Hazard Severity Zone or a wildland-urban interface area, the roof must also meet the California Wildland-Urban Interface Code.

San José requires a building permit when 25 percent or more of the roof is reroofed in any 12-month period. Less is a repair without a permit. Removing or changing solar panels or other rooftop equipment also needs an electrical or mechanical permit. The City allows at most 2 composition roof layers and asks for an engineering analysis when all coverings together weigh more than 7 pounds per square foot.

Oakland issues a Re-Roofing Certificate through its Online Permit Center. The owner, or a state-licensed contractor with a current business tax certificate, applies online and uploads the completed certificate once the work is done. A certificate covers one structure and is valid for 180 days.

On a home improvement job, the down payment should never exceed 10 percent of the contract price or $1,000, whichever is less. A contractor with a blanket performance and payment bond on file with CSLB may ask for the full amount up front. The contract should say who gets the building permits.

The C-39 roofing license covers installing and repairing surfaces that seal, waterproof and weatherproof a building, including shingles, shakes, roof tile, slate and metal roofing systems.

Old houses. In the San Francisco, Oakland and Fremont metro area, 382,633 of 1,908,554 housing units were built in 1939 or earlier, according to the 2024 American Community Survey. In the San Jose metro area it is 36,011 of 729,606.

Layers and weight. Tear-off and disposal average $50 per roofing square and can reach $150 per square for heavy materials such as concrete tile or several layers of asphalt shingles.

Damage under the old roof. In the This Old House survey, 23 percent of homeowners who found hidden damage paid more than the first estimate, against 13 percent of those who did not.

Pitch and shape. Steeper roofs have more square feet and need harnesses or scaffolding. Hips, valleys, ridges and dormers add flashing and seam work.

Chimneys, skylights and vents. Flashing and sealing around vent stacks and HVAC openings add time and material to a new roof.

Permits outside the estimate. This Old House says permit fees often do not appear in the first estimate and advises checking the contract for them.

Lifespan. Fixr gives 15 to 20 years for 3-tab shingles and 25 to 30 years for architectural shingles.

Tear-off to the deck or a new layer on top, and how many layers are on the roof today.

Roof area in squares, the material with brand and product line, and the fire class.

The price per square foot or per sheet if the decking is rotten, and photos before any of it is replaced.

Your climate zone, and either the cool roof product with its rating or the exception that applies.

Flashing at walls, chimneys and skylights: reused or replaced, and whether new counter-flashing is included.

Solar panels: who takes them off and puts them back, the electrical permit, and the cost.

Who applies for the permit or certificate, and whether the fee is in the price.

Disposal, the dumpster and street space.

The C-39 license number, so you can look it up on the CSLB site, and the payment schedule with the down payment.

Manufacturer warranty and workmanship warranty in years, the start date and the number of working days.