ADU Construction in San Francisco, CA

HMM GC Inc. builds ADUs for San Francisco homeowners looking to add livable space to their property.

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  • Adds a fully independent living unit to your existing San Francisco property without purchasing new land
  • Garage and basement conversions make use of underutilized space already on your lot
  • A completed ADU increases your property's assessed value and long-term resale potential
  • Rental income from a legal ADU can offset your monthly housing costs in a high-cost city
  • Multi-generational households gain private, separate living space for family members on the same property
  • Professional coordination through San Francisco's multi-step city review process reduces costly errors and delays
A newly constructed detached ADU in a San Francisco residential backyard, showing a finished exterior with a private entrance and landscaped separation from the main house. The unit reflects the compact, code-compliant construction style common to San Francisco infill properties.

Expert ADU Construction in San Francisco, CA

ADU construction in San Francisco gives homeowners a practical way to add a fully independent living unit to their existing property. HMM GC Inc. handles the full scope of work, from site assessment and design coordination to structural build-out, electrical, plumbing, and final inspections. We work with garage conversions, basement conversions, attached additions, and detached new builds. San Francisco's zoning rules vary by district, and the city's Planning Department holds projects to detailed building standards, including minimum ceiling heights, energy compliance, fire safety requirements, and setback rules. Navigating those layers takes a contractor who knows the local process. We manage the documentation, coordinate with inspectors, and keep your project moving through each city review stage. Whether you want to house a family member, generate rental income, or add long-term value to your property, ADU construction is one of the most direct ways to get there. Call HMM GC Inc. to talk through what your San Francisco property can support.

What's included

  • Adds a fully independent living unit to your existing San Francisco property without purchasing new land
  • Garage and basement conversions make use of underutilized space already on your lot
  • A completed ADU increases your property's assessed value and long-term resale potential
  • Rental income from a legal ADU can offset your monthly housing costs in a high-cost city
  • Multi-generational households gain private, separate living space for family members on the same property
  • Professional coordination through San Francisco's multi-step city review process reduces costly errors and delays
Licensed General Contractor
Real Estate Expertise
Detailed Project Communication
Quality Craftsmanship
Bay Area Specialist

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ADU Construction FAQ

Common questions about adu construction in San Francisco, CA.

Yes, you can build and rent an ADU in San Francisco without living on the property. California law removed the owner-occupancy requirement for ADUs effective January 1, 2024.

We build detached ADUs, attached additions, garage conversions, and basement conversions in San Francisco. The right type depends on your lot size, zoning district, and existing structure.

San Francisco does not set a single minimum lot size for ADUs. Eligibility depends on your specific zoning district and the details of your proposed project.

No replacement parking is required when you convert a garage to an ADU in San Francisco. This makes garage conversions a popular option for homeowners with limited yard space.

San Francisco ADUs must meet minimum size, ceiling height, natural light, ventilation, fire safety, and energy efficiency standards. Your project will go through building and energy inspections as part of the city approval process.

San Francisco now allows homeowners to sell newly built ADUs as separately deeded condominiums under an ordinance that took effect in 2025. This applies to single-family homes and small multi-unit buildings.

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What homeowners say.

5.0
20 Google reviews

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HMM and Hector did an outstanding job building me an ADU, from dealing with Palo Alto inspectors and permits to work quality. Communication was also outstanding. I’m very happy and have used them again for smaller jobs on the main house. Highly recommend!

Dr. Marion S Buckwalter Google review · August 2026

Hector was easy to work with from start to finish. He kept the project on schedule, stayed on budget, and communicated well throughout the entire process. The quality of work was excellent, and I would definitely recommend him to anyone looking for a reliable contractor.

Kacie McGuane Google review · August 2026

I can’t recommend HMM General Contractor highly enough. I originally hired HMM because I had a leak in my bathroom ceiling that kept returning, and two other contractors had been unable to figure out the source. I had even started calling roofing companies because no one could pinpoint where the water was coming from. A friend recommended HMM, and the owner responded promptly and came out right away to assess the situation. Within a week, his team was on site and found not one, but three separate leaks in the plumbing above the ceiling that everyone else had missed. They repaired all three leaks, coordinated with the mold remediation company, and then completed all of the repairs to restore everything. The entire process was handled professionally from start to finish. The crew was always punctual, clean, and respectful of my home. Even visiting family members commented on how friendly and courteous everyone was. That repair was a while ago, and I haven’t had a single issue since. It’s hard to find a contractor who’s responsive, thorough, and stands behind their work, but HMM absolutely delivered. I wouldn’t hesitate to hire them again or recommend them to anyone looking for an honest, high-quality contractor.

Mary Hamilton Google review · August 2026

HMM did a nice job handling everything: permitting, demolition, construction, plumbing, electrical. HMM had personal connections to many vendors in the area that helped us get the best prices and delivery times on the materials and finishes. They were flexible to work with our design and willing to go above and beyond when there was something “cool” to build. Wouldn’t hesitate to hire them again, great result.

Robert Shanks Google review · August 2026

HMM and the entire crew were fantastic to work with! They transformed our small half bath into a beautiful full bathroom, and the entire process was smooth from start to finish. The team was professional, communicative, stayed on budget, and the quality of the work exceeded our expectations. We’re so thankful for everything they did and wouldn’t hesitate to use HMM again for future projects. Highly recommend!

Anais Mathes Google review · August 2026

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Hours

  • Monday 8:00 AM - 5:00 PM
  • Tuesday 8:00 AM - 5:00 PM
  • Wednesday 8:00 AM - 5:00 PM
  • Thursday 8:00 AM - 5:00 PM
  • Friday 8:00 AM - 5:00 PM

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