Text Us
San Mateo ADU Builder logo
All Services

Garage Conversion in San Mateo, CA

Turn an underused garage into a fully permitted, code-compliant living unit.

3 - 5 months1-year workmanship warrantyFree Estimates
Text UsCall UsGet Free Estimate
Starting at $110,000|Typical range: $110,000 - $200,000
Standard one- or two-car garage conversion, based on utility upgrades.

About Our Garage Conversion Service

Converting an existing garage is one of the fastest, most affordable ways to create an ADU in San Mateo because the foundation, walls, and roof already exist. We transform the shell into a warm, code-compliant living unit with insulation, a kitchen, a full bathroom, egress windows, and its own entrance. California law protects garage conversions — cities cannot require you to replace the lost covered parking — so you keep your driveway. We manage the reframing of the garage door opening, electrical and plumbing upgrades, and Title 24 compliance from permit to final.

What's Included

Garage door wall infill
Insulation & drywall
Kitchenette or full kitchen
Full bathroom addition
Egress windows & entrance
No replacement parking required

Our Process

1

Assessment

We inspect the existing slab, framing, and utilities to plan the most cost-effective path to a permitted living unit.

2

Permit Set

We draft conversion plans meeting San Mateo egress, insulation, and energy requirements and submit for a building permit.

3

Build-Out

We infill the garage opening, insulate, add plumbing and electrical, and frame the kitchen and bath for the new unit.

4

Finish & Inspect

Flooring, fixtures, and appliances are installed, and we pass final inspection so the unit is legal to occupy or rent.

Why Garage Conversion Matters

  • Lowest cost-per-square-foot ADU option
  • Fast timeline using the existing structure
  • Keeps your driveway parking
  • Adds a legal rental or guest suite
  • Minimal disruption to your yard

Frequently Asked Questions

Will I lose my parking if I convert my garage?
You lose the covered garage space, but California law prohibits cities from forcing you to add replacement parking for a garage-to-ADU conversion, so your driveway parking stays.
Is a garage conversion cheaper than a new ADU?
Usually, yes. Because the slab, walls, and roof already exist, a conversion typically costs 40-60% less than building a detached ADU from the ground up.
Can an attached garage be converted?
Yes. Both attached and detached garages can be converted into ADUs in San Mateo, provided egress, fire separation, and energy requirements are met — all of which we handle.

Garage Conversion Service Areas

We provide garage conversion across San Mateo and the Peninsula, including:

San MateoBurlingameFoster CitySan CarlosBelmontRedwood CityMillbraeHillsboroughSan BrunoHalf Moon Bay

Get a Free Quote

Free on-site estimate

Starting at

$110,000

Standard one- or two-car garage conversion, based on utility upgrades.

Text UsCall UsRequest Online Quote

Duration

3 - 5 months

Warranty

1-year workmanship warranty

Other Services

Why Choose Us

  • Licensed & Insured
  • Satisfaction Guaranteed
  • Free Estimates
  • San Mateo Local
  • Design-Permit-Build
  • 1-Year Workmanship Warranty

What Our Customers Say

Get Your Free Estimate Today

Whether you're planning a detached backyard ADU, a garage conversion, or a home addition, our team is ready to help. Text or call us for a free feasibility review.

Text UsCall Us

Licensed

& Insured

Free

Estimates

10+

Peninsula Cities

Free

Estimates Always

Request a Free Quote

Fill out the form below and we'll contact you within 1 hour.

By submitting, you agree to our privacy policy. We never share your information.