Room Additions in San Francisco, CA
Design by M&M helps San Francisco homeowners expand their living space through carefully planned additions — managing design, permits, and construction from concept to completion.
Home Additions
Bedroom Additions
Add more sleeping capacity to the family or guests.
Dining Room Additions
Increase or develop classy eating and entertaining areas.
Family Room Additions
Make living spaces in the middle comfortable and cohesive.
Second Story Additions
Add a second story to maximize your living space
Home Office Additions
Special work areas to get work done.
Living Room Additions
More welcoming spaces to have in day-to-day life.
Bathroom Additions
Additional bathrooms as an addition to enhance convenience.
Kitchen Additions
increases or redesigns kitchen area to cook and hold meetings.
Mudroom Additions
These are practical entryways that are used to control clutter and storage.
Master suite Additions
Private, lavish retreats combined with your house.
Sunroom Additions
Well-lit areas of recreation and relaxation.
Laundry Room Additions
Roomy and neat areas to do laundry.
Home Additions
Design by M&M helps San Francisco homeowners create more functional living space through carefully planned room additions. As a design-build contractor serving San Francisco, San Mateo County, and the greater Bay Area, we manage the entire process — from early design and feasibility through permitting, construction, and final walkthrough.
On an San Francisco property, an addition is rarely just about square footage — it’s about how the home functions as a whole. As an experienced room addition contractor, Design by M&M helps homeowners expand your living space in a way that complements the existing architecture and takes full advantage of the lot.
Common addition projects we take on in San Francisco include:
- Rear additions — expanding living, kitchen, and entertaining spaces toward the garden and outdoor areas
- Primary suite additions — creating a true retreat with the space San Francisco lots allow
- Second story additions — adding an upper level where height limits and the Residential Design Guidelines allow
- Rear additions — extending toward the rear yard, the most common way to add space on a narrow city lot
- Full-home expansion projects — comprehensive additions that rework the entire footprint
Accessory Dwelling Units (ADU)
San Francisco lots leave little room for a detached backyard cottage, so most ADUs here are built inside what already exists — a garage, a ground floor, or an underused lower level — for a family member, an adult child, or rental income. As an experienced ADU builder in San Francisco, Design by M&M guides homeowners through every stage, from confirming what the lot can support to final inspection.
We design and build all types of ADUs, including:
- Garage conversions — the most common path in San Francisco, and state law bars the city from requiring replacement parking
- Attached ADUs — connected living quarters with independent access and privacy
- Junior ADUs and in-law suites — self-contained space within the existing home, ideal for multigenerational living
ADUs follow a very different approval path than additions in San Francisco, and it strongly favors the homeowner. State law requires ministerial review — no public hearing, no discretionary judgment — with a decision due within 60 days of a complete application. Compared with an addition that triggers Planning review and neighborhood notification, that difference is substantial. What still needs working out is your building: ceiling height, electrical panel capacity, sewer condition, and light and egress for the new unit. We establish all of it before design begins.
Garage Conversions
We specialize in turning underused garages and outbuildings into comfortable, fully permitted living space. Serving San Francisco and nearby communities, our team helps homeowners expand what their property can do — without adding new structures to the lot.
Popular garage conversion projects include:
- Converting a detached garage to an ADU or guest quarters
- Creating a home office, studio, or gym
- Transforming an outbuilding into flexible bonus space
Garage conversions often look simple from the outside, but they involve real construction and compliance work: insulation, electrical upgrades, plumbing (for ADU conversions), egress requirements, and city permitting. We manage those details from the start, so the finished space is safe, legal, and built to the same standard as the main home.
Design Build
Design by M&M is a design build contractor, which means one team manages your project from concept to completion. Instead of coordinating separate architects, designers, engineers, and builders, you work with a single team responsible for the entire outcome.
Our design-build approach includes:
- Consultation and property review
- Custom designs shaped around your goals, property, and budget
- Architectural planning and engineering coordination
- Town permitting and approvals
- Construction scheduling and project management
- The build phase, through final walkthrough
In San Francisco this matters more than almost anywhere. Most additions need a Planning Department approval letter before the building permit application can even be filed, and any expansion of the building envelope triggers neighborhood notification under Section 311 — a 30-day window during which a neighbor may request Discretionary Review. Designing with the Residential Design Guidelines in view from the first sketch, rather than revising after comments, is what keeps a project moving. When one team owns both design and building, nothing gets lost between the drawing and the finished result.
Home Remodeling
As a remodeling company serving San Francisco, we focus on substantial renovation projects that bring the city’s older housing stock up to modern standards of comfort, efficiency, and function. Much of San Francisco was built before 1940, and those homes carry real character alongside real problems — compartmentalized layouts, dark interior rooms, knob-and-tube wiring, galvanized plumbing, and framing that predates current seismic standards.
Our remodeling services include:
- Whole house renovation — comprehensive updates to layout, systems, and finishes across the residence
- Kitchen remodels — typically as part of larger layout improvements or expansions of the home’s main living areas
- Major renovations — reworking floor plans, modernizing structural and mechanical systems, and restoring older homes to their potential
- Renovation paired with additions — improving the existing home while expanding its footprint
Our remodeling process follows the same design-build structure as our additions and ADU work: feasibility first, then design, budget alignment, permitting, and construction — all managed by one team with clear communication throughout.
Design in 3 simple steps
Consult & Design
We start with a thorough consultation, creating custom designs tailored to your style and needs.
Expert Construction
Our skilled team manages every detail, from demolition to installation, ensuring precision and quality.
Enjoyment
We complete your project with meticulous attention, ensuring your complete satisfaction and a stunning new kitchen.
Frequently Asked Questions
If you don’t see your question answered here, please don’t hesitate to contact us directly – we’re always happy to help!”