Building Permit Guide for San Mateo County (2026)

Why Building Permits Matter in San Mateo County

Whether you are remodeling a kitchen in Burlingame, building an ADU in Redwood City, or constructing a custom home in Woodside, a building permit is the legal foundation of your project. Permits exist to protect you, your family, and your investment by ensuring that all construction meets California’s building, fire, electrical, plumbing, and energy codes.

Skipping permits creates risks that far outweigh the fees and timeline involved. Unpermitted work can result in fines, stop-work orders, forced demolition, insurance claim denials, and serious complications when you sell or refinance your home. This guide walks through every step of the building permit process in San Mateo County so you can approach your project with clarity and confidence.

Types of Building Permits

San Mateo County issues several categories of permits depending on the scope and nature of your project. Understanding which permits apply to your work is the first step in the process.

Building Permits

A standard building permit covers structural work, including new construction, additions, remodels, and alterations that affect the structural integrity, layout, or use of a building. If your project involves removing or adding walls, changing the roofline, or converting a space to a different use, a building permit is required.

Trade-Specific Permits

In addition to a building permit, most projects also require one or more trade-specific permits:

• Electrical permit: Required for new wiring, panel upgrades, circuit additions, and lighting installations
• Plumbing permit: Required for new or relocated supply lines, drain/waste/vent piping, water heater installations, and fixture additions
• Mechanical permit: Required for HVAC system installation, ductwork modifications, and ventilation changes

Planning Permits

Some projects require a planning permit before you can apply for a building permit. Planning permits address zoning compliance, land use, environmental review, and design standards. If your project requires both a planning permit and a building permit, the planning permit must be approved first.

Combination Permits

For larger projects that involve building, electrical, plumbing, and mechanical work, a combination permit may be available. This consolidates multiple permits into a single application, simplifying the process for comprehensive remodels and new construction.

City vs. County Jurisdiction: Where to Apply

One of the most important details to clarify before starting your permit application is which jurisdiction handles your permit. San Mateo County contains 20 incorporated cities and towns, each with its own building department.

Incorporated Cities

If your property is within city limits, you apply through that city’s building department, not the County. Major incorporated cities in San Mateo County include:

• San Mateo, Redwood City, Daly City, South San Francisco, San Bruno
• Burlingame, Foster City, Belmont, San Carlos, Menlo Park
• Millbrae, Pacifica, Half Moon Bay, Brisbane, Colma
• East Palo Alto, Hillsborough, Atherton, Portola Valley, Woodside

Each city maintains its own fee schedule, submission requirements, plan check timelines, and inspection protocols. Contact your city’s building department directly for jurisdiction-specific guidance.

Unincorporated County Areas

If your property is in an unincorporated area, the San Mateo County Planning and Building Department handles your permits. Unincorporated communities include areas such as North Fair Oaks, Emerald Lake Hills, Devonshire, Sequoia Tract, and parts of the coastal region near Montara and Moss Beach.

The County’s Development Review Center (DRC) processes all permit applications for unincorporated areas. You can verify whether your property falls under county or city jurisdiction by contacting the DRC or checking your property records.

Required Documents for Your Application

A complete application is the single most effective way to avoid delays. The San Mateo County Planning and Building Department requires the following documentation for building permit applications.

Construction Plans

All plans must be submitted in PDF format through the County’s online portal. Your plan set should include:

• Site plan showing the existing structure, proposed work, property lines, setbacks, and easements
• Floor plans for existing and proposed conditions
• Exterior elevations showing the project’s impact on the building’s exterior
• Building sections detailing wall assemblies, structural connections, and ceiling heights
• Construction details for footings, framing connections, waterproofing, and finishes

Structural Calculations

A licensed structural engineer must provide structural calculations demonstrating that the proposed work meets current California Building Code (CBC) requirements. This includes foundation design, framing specifications, and seismic resistance analysis for the Bay Area’s seismic zones.

Title 24 Energy Compliance

California’s Title 24, Part 6 (the Energy Code) applies to all new construction, additions, and most remodels. As of January 1, 2026, the 2025 Energy Code is in effect, with roughly 30% more stringent requirements than the previous code cycle. Your application must include a completed CF-1R (Certificate of Compliance) form prepared by a qualified energy consultant.

Workers’ Compensation Documentation

Contractors or owner-builders applying for permits must provide proof of Workers’ Compensation insurance each time a permit is applied for. If you are an owner-builder performing the work yourself without employees, you may sign a Workers’ Compensation exemption form instead.

Survey Requirements

A property survey is required for the construction of new buildings, additions, accessory structures, decks, swimming pools, and any alterations or remodels that exceed 50% of the valuation of the existing structure. Coordinate with a licensed surveyor early in the process, as survey scheduling can add time to your timeline.

Additional Documentation

Depending on your project and property, you may also need:

• Geotechnical (soil) report for properties in hillside areas or with known soil conditions
• Fire district clearance if your property falls within a fire authority’s jurisdiction
• “Will Serve” letter from your water and sewer provider
• Tree removal or protection plan for projects affecting protected trees
• Grading and drainage plans for projects that alter the site’s topography

The Application Process Step by Step

Step 1: Determine Your Jurisdiction

Confirm whether your property is in an incorporated city or an unincorporated area. This determines where you submit your application. If you are unsure, email the County’s building counter at buildingcounter@smcgov.org to verify.

Step 2: Check Whether Your Project Needs a Planning Permit

Some projects require planning approval before you can apply for a building permit. Zoning compliance, design review, variances, and conditional use permits all fall under planning. If your project needs both permits, the planning permit must come first.

Step 3: Prepare Your Plans and Documents

Engage a licensed architect, structural engineer, and Title 24 energy consultant to prepare your complete plan set and supporting documents. A design-build firm like Custom Home coordinates all of these disciplines, ensuring that plans are complete and consistent across every required discipline before submission.

Step 4: Submit Your Application Online

Building permit applications for unincorporated San Mateo County must be submitted online through the County’s Online Permit Center, powered by Accela. Create an account, select the appropriate permit type, and upload your completed application forms and plan set in PDF format.

For properties within incorporated cities, submit through that city’s online permit portal. Many cities in San Mateo County also use Accela or similar platforms.

Step 5: Initial Application Review

County staff reviews your application to determine completeness, generally within five business days for building permits. During this step, initial fees for the project are assessed. If your application is incomplete, you will receive a notification specifying what additional information is needed.

Step 6: Plan Check and Referral

Once your application is accepted as complete, the County refers it to the appropriate review agencies. Depending on your project, reviewers may include Building, Public Works, Fire, Civil/Drainage, and Geotechnical departments. Plan check agencies generally complete their reviews within 30 days of receiving the application.

Step 7: Corrections and Resubmittal

If reviewers identify issues, you will receive plan check comments listing all required corrections. Revise your plans, address every comment, and resubmit. Allow a 30-day timeframe for the County’s review of each resubmittal. Submitting complete, code-compliant plans on the first attempt is the best way to minimize this back-and-forth.

Step 8: Fee Payment and Permit Issuance

Once your plans are approved, the County calculates your final fees. After all fees are paid, your building permit is issued and construction can begin.

Understanding Permit Fees

Building permit fees in San Mateo County are based on the project’s construction valuation, which must include both materials and labor costs. Even for owner-builder projects, labor costs must be included in the valuation.

Fee Components

A typical residential permit includes several fee categories:

• Building permit fee: Calculated from a tiered schedule based on total project valuation
• Plan check fee: Assessed as a percentage of the building permit fee
• Electrical, plumbing, and mechanical fees: Minimum fees apply for each trade
• Filing fee and microfilming charge: Administrative costs included with every permit
• Affordable Housing Impact Fee: The San Mateo County Board of Supervisors assesses this fee on certain residential and non-residential development to offset the impact of new development on the need for affordable housing

Fee Estimates

The County provides approximated fees that give an estimated, rounded total based on the permit fee and anticipated review costs from the adopted Planning Service Fee Schedule. These approximated fees are not exact amounts for specific projects and may be higher or lower than the actual fees assessed.

For current fee schedules and project-specific estimates, contact the San Mateo County Building Counter at (650) 599-7310. Office hours are 8:00 am to 4:00 pm, Monday through Thursday (closed 12:00 to 1:00 pm for lunch), and closed Friday through Sunday.

Required Inspections

Once your permit is issued, your project must pass inspections at key construction milestones. Never cover any work until a building inspector has approved it.

Common Inspection Types

The specific inspections required depend on your permit type, but residential projects typically include:

1. Foundation/footing: Verify excavation, formwork, and steel reinforcement before concrete is poured
2. Underfloor/underslab: Inspect plumbing, moisture barriers, and gravel base before the slab is poured
3. Framing: Verify structural framing, shear walls, hold-downs, and connections match approved plans
4. Rough electrical: Inspect wiring, boxes, panel connections, and grounding before walls are closed
5. Rough plumbing: Inspect supply lines, drain/waste/vent piping, and fixture connections
6. Rough mechanical: Inspect HVAC ductwork, equipment, and refrigerant lines
7. Insulation and energy: Verify insulation values, air sealing, and window specifications match the Title 24 report
8. Final inspection: A comprehensive walkthrough confirming all work is complete, smoke and carbon monoxide detectors are installed, and the space is safe for occupancy

Scheduling Inspections

The San Mateo County Planning and Building Department operates an automated inspection scheduling system that provides 24-hour access to schedule or cancel inspections and check permit status. Inspections are available between 8:00 am and 3:30 pm. After 7:30 am on the day of your inspection, you can check online for your three-hour estimated time window.

Status updates and inspection results are available through the Online Permit Center.

Using the Online Permit Center

The San Mateo County Online Permit Center, powered by Accela, is the central hub for all permit activity in unincorporated areas. Through the portal, you can:

• Submit new building permit applications
• Upload plans and supporting documents in PDF format
• Track your application’s review status in real time
• View plan check comments and correction requests
• Schedule and manage inspections
• Pay fees online
• Access inspection results and permit history

The portal is available at aca-prod.accela.com/smcgov. The County advises applicants to watch out for fake websites imitating the permit portal. Always verify you are on the official County site before submitting personal or project information.

Common Reasons for Permit Delays

Understanding the most frequent causes of delay helps you avoid them:

• Incomplete applications: Missing documents, incorrect forms, or plans not in PDF format
• Zoning non-compliance: Setback violations, lot coverage exceedance, or height limit issues not identified before submission
• Missing planning approval: Applying for a building permit before obtaining a required planning permit
• Structural calculation errors: Undersized members, missing connection details, or incomplete seismic analysis
• Title 24 non-compliance: Energy calculations that do not meet the 2025 code requirements
• Multiple correction cycles: Each round of plan check comments adds up to 30 days
• Missing clearances: Fire district, utility, or environmental clearances not obtained before or during plan check
• Workers’ Compensation omission: Failing to include proof of insurance or a signed exemption form

How Custom Home Handles the Permit Process

Navigating San Mateo County’s permitting requirements is one of the most time-consuming parts of any construction project. At Custom Home, we manage the entire permit process as part of our Phase 1 (Design) scope. Our team prepares complete, code-compliant plans, coordinates with structural engineers and Title 24 consultants, submits the application through the appropriate portal, responds to all plan check comments, and schedules every required inspection during construction.

Our experience with Bay Area building departments means we submit plans that pass plan check with minimal corrections. This reduces your timeline by weeks and eliminates the frustration of managing multiple correction cycles. You get a single point of contact for the entire process instead of coordinating between separate architects, engineers, energy consultants, and permit expediters.

If you are planning a remodel, addition, ADU, or custom home in San Mateo County and want a team that handles permits, design, and construction under one roof, contact us today to discuss your project. We will walk you through the requirements specific to your property and jurisdiction so you know exactly what to expect before you commit.