A studio of drafters, builders, and Angelenos.
We started Golden State ADU in 2018 with a single conviction: a backyard cottage should feel as considered as the house in front of it. Seven years and California projects later, we still believe it.
Drawn before built
Every project begins with a real architect at the table. We model setbacks, easements, and Title 24 envelopes before we ever quote construction. The drawing is the contract.
One crew, one foreman
We don't subcontract the foundation, the framing, and the finish to three different teams who've never met. The same foreman runs your project from groundbreak to final inspection.
Permits in plain English
LADBS, LA County, Beverly Hills, Santa Monica, Pasadena — each city has its own quirks. We translate them into a calendar you can plan a rental against.
Quiet sites
Driveways swept on Friday. Music off after 4pm. Neighbors notified the week before noisy phases. The build is loud enough; we don't add to it.
05 — Verifiable
License, address, accreditation.
- Headquarters
- 555 California Street, San Francisco, CA 94104
- Insurance & Bonding
- Available on request
Open Monday–Friday, 9am–6pm PT. Visits by appointment.
License, bond, and insurance certificates shared during your consultation.
"Build the thing your client would build if they had thirty years of hindsight." — house motto, written above the studio door.
Begin a project →FAQ
About the studio — questions worth asking before you hire anyone
Who are Golden State ADU and what does the studio actually do?
Golden State ADU is a California residential design-build studio working on ADUs, garage conversions, custom homes, teardown and fire rebuilds, hillside projects, SB9 lot splits, and 2–6 unit small multifamily across Los Angeles County and the San Francisco Bay Area. We hold CSLB #1156772 and carry full general liability and workers' comp; certificates are shared during your consultation.Do you only design, only build, or both?
Both — under a single contract. One licensed entity owns architecture, structural, MEP coordination, permit runner, site supervision and warranty. That's how we keep change orders under 4% of contract value (industry average is 12–18%) and avoid the classic 'designer blames builder' loop.How do I verify your license and insurance?
California contractor license details are available on request and can be confirmed at cslb.ca.gov, which shows current bond status, workers' comp carrier and any open complaints for any verified CSLB number. After a signed agreement, we email a full insurance certificate naming you as additional insured.What makes you different from a general contractor who 'also builds ADUs'?
Three things. (1) Single-product focus: we only build ADUs and small additions, so our suppliers, plan-check reviewers and inspectors know us by name. (2) Fixed-fee design phase with a published schedule before any construction commitment. (3) A documented post-occupancy 12-month walkthrough — most GCs disappear at certificate of occupancy.Where are your projects located?
Two studios: Los Angeles desk (covering LA, Orange, Ventura, San Bernardino) and Bay Area desk (covering San Francisco, Alameda, Santa Clara, Contra Costa, San Mateo, Marin). Both run the same playbook with locally-permitted teams. See the Locations index for service maps and recent projects per region.What size projects do you take on?
Detached ADUs 400–1,200 sq ft, garage conversions 200–600 sq ft, JADUs up to 500 sq ft, and primary-home additions up to 1,500 sq ft when bundled with an ADU. We don't take on full custom homes — staying narrow is the entire point.What's your typical project budget?
Most signed projects land between $250K and $480,000 all-in. Garage conversions start around $145,000, detached new builds typically $280,000–$400,000, two-story detached or hillside lots $400,000–$480,000. Every estimate is itemized by CSI division — no lump-sum mystery numbers.How do I actually get started?
Submit your address via Contact for a free 30-minute feasibility call. Within one business day you receive a written brief: which ADU types your lot can support, an estimated cost band, a permit timeline for your jurisdiction, and a fixed fee for full schematic design. No obligation, no pressure.