Do I need a permit in Millbrae, California?
Millbrae sits in the San Francisco Bay Area's most complex permitting environment. The city enforces the 2022 California Building Code, which is stricter than the national standard in seismic design, energy efficiency, and water conservation. Most residential work — decks, fences, electrical, plumbing, HVAC, solar, room additions, finished basements — requires a permit. The major exception is owner-builder work in specific categories, though electrical and plumbing always need a licensed contractor and separate trade permits. Millbrae's Building Department processes permits through the city hall system, with typical residential permits taking 2–4 weeks for plan review and approval. Online filing is available through the city's permit portal, which streamlines the process for routine projects. The city's coastal-zone location (climate 3B-3C) means your project might trigger additional environmental review or coastal-access requirements. Getting a quick answer from the Building Department before you order materials saves weeks of rework.
What's specific to Millbrae permits
Millbrae enforces the 2022 California Building Code with San Mateo County amendments. This means seismic requirements are stringent — your deck, fence, or room addition will need to account for seismic forces that don't matter in most of the country. If you're adding a structure or modifying the foundation, expect the inspector to ask about soil conditions and lateral bracing. The city's Bay Mud substrate (in the flatter areas) and clay-heavy soils in higher zones mean footing depths, backfill, and drainage are scrutinized carefully.
California's Title 24 energy code is embedded in every permit decision. New windows, doors, insulation, HVAC equipment, water heaters, and pool equipment must meet current Title 24 standards. A 20-year-old HVAC unit cannot be replaced with an identical model — it must meet today's efficiency ratings. Solar installations trigger additional Title 24 paperwork and a separate solar permit. This adds 1–2 weeks to the timeline if you're doing energy-related work.
Owner-builder work is allowed under California Business and Professions Code Section 7044, but with limits. You can pull permits for your own residential projects, but electrical and plumbing work must be done by licensed contractors, and those trades file their own permits. DIY work on framing, roofing, decking, or drywall is permitted; DIY electrical, plumbing, gas, or HVAC work is not. If the inspector finds unlicensed work, the entire permit can be voided and you'll be ordered to remove or redo the work at contractor rates.
Millbrae's proximity to the Bay and the San Andreas Fault means some projects trigger Phase I environmental screening or coastal-zone review. Decks, fences, and outbuildings in certain areas may require a categorical exemption letter or a minor use permit. Check with the Building Department at the start — a 10-minute call can flag whether your lot is in a sensitive zone and save you weeks of surprises during plan review.
The city uses an online portal for permit intake. Most residential projects can be filed digitally with plans, a filled-out application, and proof of property ownership. Over-the-counter permits (small fences, siding, roofing) can sometimes be approved in a single office visit, but plan-heavy projects (additions, decks with ties to existing structures) go through formal plan review. Bring originals to the office and keep a copy for your records.
Most common Millbrae permit projects
These projects account for the majority of residential permit applications in Millbrae. Each has specific local triggers, fees, and timelines. Click through for detailed local guidance on what you need to file.
Decks and patios
Any attached deck over 200 square feet or over 30 inches high requires a permit and structural engineer sign-off. Detached decks and patios need permits unless they're at-grade (less than 12 inches high) and under 200 square feet. Bay Mud makes footing inspection critical — expect delays if your soil report shows high water content.
Fences
Front-yard fences over 3 feet or side/rear fences over 6 feet require a permit. All masonry walls over 4 feet need a permit. Property-line certification is mandatory — the inspector will compare your fence location to the recorded plat. Many Millbrae rejections happen because the applicant assumed the old fence was on the property line.
Room additions and remodels
Interior remodels with electrical or plumbing changes, exterior additions, or any work changing the home's footprint requires a full permit with plans and an engineer. Millbrae requires Title 24 compliance, meaning new insulation, windows, and doors must meet current efficiency standards. Plan review averages 3–4 weeks.
Solar panels
California's solar mandate means residential solar gets expedited permitting, but you still need a separate solar permit. Title 24 requires a solar-readiness assessment or actual installation. Most installers handle the permit; if you're doing it yourself, expect 2–3 weeks for plan review.
HVAC, water heaters, and electrical
HVAC replacement and water-heater installation require permits and trade licenses. Electrical work — panel upgrades, new circuits, outlet additions — must be done by a licensed electrician who files the permit. Homeowners cannot pull electrical permits in California. Plumbing additions also require a licensed plumber.
Finished basements
Finishing a basement requires a permit if you're adding framing, insulation, drywall, or electrical. Egress windows are mandatory if the space will be a bedroom. Bay Mud and high groundwater in some Millbrae neighborhoods mean waterproofing and drainage are scrutinized carefully.
Millbrae Building Department contact
City of Millbrae Building Department
City of Millbrae, Millbrae, CA (contact city hall for specific building division address)
Call Millbrae city hall and ask for Building and Planning; exact number available via city website
Typical: Monday–Friday, 8 AM–5 PM (verify hours when you call; many Bay Area cities have limited walk-in hours)
Online permit portal →
California context for Millbrae permits
California's building code is the 2022 CBC, which includes strict seismic, energy, and water-conservation rules. Title 24 energy standards are non-negotiable — any project touching HVAC, windows, doors, insulation, water heating, or pool equipment must comply. California also prohibits most owner-builder electrical and plumbing work; even though you can pull your own building permit, you cannot do the electrical, plumbing, gas, or HVAC work yourself. Licensed contractors file their own trade permits, and the inspector expects to see a valid contractor license on site. California's Solar Rights Act and Title 24 solar mandate mean residential solar is streamlined but still requires a separate solar permit. Finally, California's seismic retrofit laws (Earthquake Safety Implementation Program) do not yet mandate retrofits in Millbrae, but the code enforces seismic anchoring and bracing on new work and major remodels. If you're doing foundation work, lateral bracing, or adding stories, expect structural engineering review and seismic calculations.
Common questions
Can I pull a permit myself in Millbrae, or do I need a contractor?
You can pull a building permit under California's owner-builder exemption (B&P Code Section 7044), but electrical and plumbing work must be done by licensed contractors. Framing, roofing, decking, drywall, and siding are allowed as owner-builder work. If the inspector finds unlicensed electrical or plumbing, the permit is voided and you'll be ordered to hire a contractor to redo the work at full cost.
How long does a Millbrae permit take?
Over-the-counter permits (small fences, re-roofing, siding) can be approved in one office visit. Plan-review projects (decks, additions, solar) average 2–4 weeks from submission to approval, depending on whether the city asks for revisions. Once approved, you have 180 days to start work and 12 months to finish.
What does a Millbrae permit cost?
Fees are typically 1–2% of the project valuation, plus a base application fee ($100–$200 for simple projects). A $15,000 deck permit might run $250–$400. Solar and energy-related permits are processed at reduced fees under California law. Get a fee quote from the Building Department before you submit — fees depend on scope.
Do I need a permit for a fence in Millbrae?
Yes, if it's over 6 feet in the rear or side yard, or over 3 feet in the front. All masonry walls over 4 feet need permits. Property-line certification is mandatory — the city will compare your fence location to the recorded parcel map. Many applications are rejected because the applicant didn't mark the property line correctly on the site plan.
What if my project is in a coastal zone or environmental-sensitive area?
Millbrae's coastal proximity means some projects trigger environmental review or a categorical exemption letter. Decks, fences, and outbuildings in certain zones may need additional approvals. Call the Building Department or check the city's coastal-zone map before you start. A 10-minute call can save weeks of delays.
Do I need to hire an engineer for my deck in Millbrae?
If your deck is attached, over 30 inches high, or over 200 square feet, a structural engineer must stamp the plans. The 2022 CBC requires seismic calculations for decks. Even small detached decks may need engineering if the soil is poor or the posts bear on Bay Mud. The permit application will clarify whether engineer sign-off is required.
Can I replace my HVAC or water heater without a permit?
No. HVAC and water-heater replacement require permits in California. The new equipment must meet Title 24 efficiency standards and may trigger gas-line or electrical upgrades. A licensed HVAC contractor files the permit. If you try to do this without a permit, you'll face fines and the city may order the work removed.
What is Title 24 and how does it affect my Millbrae permit?
Title 24 is California's energy code. Any work involving windows, doors, insulation, HVAC, water heating, or pool equipment must meet current Title 24 standards. Your 20-year-old HVAC unit cannot be replaced with an identical model — it must be a new, efficient unit. Solar installations, EV chargers, and heat-pump systems trigger additional Title 24 documentation. Title 24 compliance typically adds 1–2 weeks to the permit timeline.
Ready to file in Millbrae?
Before you start, call the Millbrae Building Department to confirm permit requirements and get a fee estimate. Have your address, property-line survey, and a sketch of the project ready. If you're planning an addition, deck, or solar installation, get plans stamped by an engineer — Millbrae always requires engineer sign-off for structural work. File online through the city portal if possible; it's faster than in-person submission. Keep copies of your permit and all inspection sign-offs — you'll need them for future sales or insurance claims. If your application is rejected, the city will tell you why; plan for one revision cycle (1–2 weeks) before final approval.