Our ADU Services
From garage conversions to ground-up backyard homes, we handle every kind of accessory dwelling unit in San Mateo — design, permits, and construction under one roof.
New ADU Construction
Ground-up detached ADUs — full-service design, permitting, and construction on your San Mateo lot.
Garage Conversion
Turn an underused garage into a fully permitted, code-compliant living unit.
Detached Backyard ADU
Private backyard cottages that add space, privacy, and value to your home.
Prefab & Modular ADU
Factory-built modular ADUs installed fast, with less on-site disruption.
ADU Design & Permitting
Complete design and permit management — plans, plan check, and approvals.
Junior ADU (JADU)
Convert a bedroom into a compact 500 sq ft junior ADU within your home.
Home Additions
Room additions and second-story expansions that grow your existing home.
Why San Mateo Homeowners Trust Us
We stand behind our work with industry-leading guarantees.
Licensed & Insured
Full liability coverage
Top Rated
San Mateo's ADU experts
Satisfaction Guaranteed
1-year workmanship warranty
Free Estimates
No-obligation quotes
Design-Build
One contractor, start to finish
Experienced Team
Trained professionals
How It Works
Building an ADU with us is simple. Here's our clear 3-step process.
Free Consultation
Text or call us for a free feasibility review. We discuss your goals, budget, and lot, and tell you what type of ADU your property can support.
Design & Permits
We produce construction drawings and manage the full submittal to the City of San Mateo or the County, handling every plan-check correction.
We Build It
Our licensed crews build your ADU from foundation to finish, keep the site clean, and hand you a permitted, move-in-ready unit.
Transparent Pricing
No hidden fees, no surprises. Get a clear price before we start. All estimates are free.
Conversion & JADU
Fastest, most affordable path
From $45,000
- Junior ADU (up to 500 sq ft)
- Garage-to-ADU conversion
- Uses existing structure
- Kitchenette or full kitchen
- Private entrance
- 2 - 5 month timeline
Detached Backyard ADU
Most popular for added value
From $230,000
- Ground-up detached unit
- Up to 1,200 sq ft
- Independent kitchen & bath
- Separate utility metering
- Full design & permitting
- 6 - 10 month turnkey build
- 1-year workmanship warranty
Prices vary based on ADU type, size, site conditions, and finishes. Text or call for a free, no-obligation estimate.
Trusted Brand Partners
We Work With the Best
San Mateo ADU Guide
California's ADU laws make it easier than ever to add a unit in San Mateo. Here's what every homeowner should know before building.
By-Right Approval
California's statewide ADU law makes compliant ADUs ministerial — no public hearing, no neighbor veto, and a mandatory 60-day decision. We design specifically to qualify for this by-right path in San Mateo.
What Your Lot Allows
Detached ADUs are allowed up to 1,200 sq ft, junior ADUs up to 500 sq ft, and cities must permit at least 800 sq ft with only 4-foot side and rear setbacks. Most San Mateo lots qualify — we confirm during feasibility.
Parking & Utilities
If your property is near transit or you're converting a garage, added parking is waived. New detached ADUs can have their own utility meters, address, and lease — we handle the connections and metering.
ROI on the Peninsula
ADUs add significant property value and strong rental income across San Mateo County. A backyard unit or converted garage can offset your mortgage while giving family a private, independent place to live.
Frequently Asked Questions
Got questions about building an ADU in San Mateo? We've got answers.
Yes. Every ADU requires a building permit, but California's statewide ADU law makes approval ministerial (by-right) for compliant projects — no public hearing and a 60-day decision. We prepare the full permit set and manage the City of San Mateo / San Mateo County submittal for you.
Serving San Mateo & the Peninsula
We build ADUs, garage conversions, and additions for homeowners throughout San Mateo County. Find your city below for local ADU construction.
San Mateo
Full ADU design, permitting, and construction across Hillsdale, San Mateo Park, Baywood, and Aragon.
Free on-site estimatesBurlingame
Detached backyard ADUs and garage conversions for Burlingame's classic homes and tree-lined lots.
Design-build serviceFoster City
Backyard ADUs and additions for Foster City's waterfront and lagoon-side neighborhoods.
Ministerial approval pathSan Carlos
ADU construction and garage conversions across White Oaks, Howard Park, and Devonshire.
Licensed & insuredBelmont
Hillside-savvy ADU and addition builds for Belmont's sloped lots and wooded neighborhoods.
Sloped-lot experienceRedwood City
Detached ADUs, JADUs, and additions throughout Redwood City's diverse neighborhoods.
Full permit management