San Mateo · San Mateo County
Commercial Roofing in San Mateo: Apartment, Condo and Commercial Roofs
Apartment, condo and commercial roofs across San Mateo.
- Free roof condition report
- Good, better and best bid options
- Certificate of insurance within 24 hours of request
San Mateo is an apartment city
The California Department of Finance counts 43,932 housing units in San Mateo, and 17,778 of them are in buildings of 5+ units, about 40% and the most of any San Mateo County city. Another 2,658 are in 2–4 unit buildings and 4,546 are single-attached, in a city of 104,020 (January 1, 2026).
What that means on the roof
Many low-slope roofs sit over occupied units. Rooftop equipment, roof hatches and parapet drains are the usual leak points, and work gets phased around residents. See roofing for property managers and HOA and condo roofing.
Illustrative image, not a completed project.
San Mateo's Express reroof permit
- The City of San Mateo lists reroofs as Express Building Permits: no plan check and no construction drawings, issued at the Building Division counter or through the city's Online Permit Center (City of San Mateo, Express Building Permits).
- The building permit application asks for the reroof's number of squares and the roofing material, so measure the scope before applying.
- The city inspects the work.
Projects tied to code enforcement, stop-work notices, active planning applications or right-of-way impacts get a full review instead (City of San Mateo, Projects Eligible for OTC and VOTC Review, rev. 11/14/2025).
San Mateo weather on flat roofs
There's no NOAA normals station in the city, but the two nearest bracket it: SFO to the north, 19.64 inches a year with December wettest (4.14 inches), and Redwood City to the south, 19.02 inches with 86% falling November through March (1991–2020 normals, NCEI). So: about 19 to 20 inches a year, almost all of it November through March.
Winter storms test parapet drains and scuppers, and marine air ages exposed fasteners and sheet metal. See flashing, sheet metal and drainage.
Title 24 on commercial re-roofs
San Mateo ZIPs 94401 and 94403 are in climate zone 3 (CEC ZIP list). On nonresidential low-slope roofs, California's Energy Code applies cool-roof requirements when the area replaced, recovered or recoated is more than 50% of the roof or more than 2,000 square feet, whichever is less (Energy Code §141.0(b)2B). The new surface must be a CRRC-rated product that meets the code's reflectance and emittance minimums, and a re-roof over conditioned space in Bay Area climate zones 3, 4 and 12 generally also needs R-23 continuous insulation (BayREN, Table 141.0-C). Recoats are exempt from the insulation rule. Our Title 24 re-roof guide walks through the trigger, the cool roof values and the insulation rule.
Common San Mateo roof problems
Ponding at parapet drains
Water held behind parapets when drains and scuppers clog. See commercial roof repair.
Flashing at rooftop units and hatches
Failed flashing where equipment and access hatches meet the roof.
Worn coatings on older built-up roofs
Coatings that have weathered through. See restoration and coatings.
Nearby
Redwood City: south, with its own NOAA station and weekday-only construction hours.
South San Francisco: north, the Peninsula's largest lab market, with a detailed re-roofing handout.
Burlingame, Foster City and Belmont: neighboring bay-side cities.
The rest of the county: commercial roofing in San Mateo County.
Frequently Asked Questions
Yes, but in most cases it's quick. The City of San Mateo lists reroofs as Express permits, with no plan check and no construction drawings. They're issued at the Building Division counter or online. The application asks for the number of squares and the roofing material, and the city inspects the work.
Commercial Roofing Inc. repairs, inspects, coats and replaces low-slope roofs on San Mateo apartment, condo and commercial buildings. You get photos of the problems, a line-item scope and good, better and best options, and a COI within 24 hours of request. Call (408) 770-5992 or request a bid.
In early fall, before the rainy season. NOAA's 1991–2020 normals for SFO and Redwood City, the stations on either side of San Mateo, show about 19 to 20 inches a year, almost all of it November through March. Clear drains and scuppers and fix flashing before the first storm.
Let's get started
Request a bid for a San Mateo building
Tell us the property, the building type and what you need. Bid invites and plans are welcome. For an active leak, call.
- (408) 770-5992Calling is fastest for an active leak