Room Additions in Redwood City, CA
Design by M&M helps Redwood City 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 Redwood City homeowners create more functional living space through carefully planned room additions. As a design-build contractor serving Redwood City, 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 Redwood City 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 Redwood City 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 Redwood City lots allow
- Second story additions — adding an upper level, which requires an Architectural Permit before building permit review
- Side additions — extending wings for guest quarters, offices, or family space where setbacks allow
- Full-home expansion projects — comprehensive additions that rework the entire footprint
Accessory Dwelling Units (ADU)
Redwood City lots accommodate detached ADUs on many properties, and the city publishes its own ADU handout and checklist — a sign of how routine these projects have become here. Homeowners build them for aging parents, adult children, or rental income. As an experienced ADU builder in Redwood City, 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:
- Detached ADUs and guest houses — standalone units designed to complement the main residence and landscape
- 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 ministerial path in Redwood City, meaning staff-level review rather than a public hearing, with a decision due within 60 days of a complete application under state law. Cities cannot require replacement parking when you convert a garage. What still needs establishing is your specific parcel — setbacks, easements, sewer and water capacity, electrical panel headroom, and any overlay affecting the property. We work that out before design begins.
Garage Conversions
We specialize in turning underused garages and outbuildings into comfortable, fully permitted living space. Serving Redwood City 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
Redwood City sequences its reviews in a way that catches homeowners out. A second-story addition requires an Architectural Permit from Planning, and that has to be obtained before you can schedule the One Stop Plan Review appointment for the building permit — the two steps are consecutive, not concurrent. Structural review then runs roughly six to eight weeks. Additions of 500 square feet or more also require paying the Sequoia Union High School District impact fee, with proof of payment needed before the permit will issue. Designing with that sequence in view from the start is what keeps a project on schedule.
Home Remodeling
As a remodeling company serving Redwood City, we focus on substantial renovation projects that bring older homes up to modern standards of comfort, efficiency, and function. Redwood City has a wide range of housing stock, from pre-war bungalows in the older neighborhoods to post-war ranch homes further out, and both tend to share the same issues — closed-off kitchens, undersized bathrooms, aging electrical and plumbing, and layouts built for a different era.
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!”
Larger projects take longer, and Redwood City projects tend to be larger. Most additions run from several months to a year or more from initial design through construction, depending on scope, design complexity, and town review. We build permitting and planning review into the schedule from the beginning and give you a realistic timeline during your consultation.
Yes. Additions, ADUs, and conversions in Redwood City require permits through the town, and many projects also involve planning review for setbacks, height, floor area, and landscape screening. Redwood City's review standards are more involved than many neighboring cities, which makes early planning especially valuable. As a design-build contractor, we prepare the plans, manage submittals, and guide the project through approvals on your behalf.
Redwood City places strong protections on heritage and mature trees, and their locations can influence where an addition, ADU, or driveway can go. Tree surveys, protection plans, and careful siting are often part of the design process. We account for these constraints during feasibility, so the design respects the landscape and moves through town review smoothly.
The biggest cost factors are the size of the project, structural work required, site conditions, finish level, and whether utilities or the foundation need upgrades. On larger Redwood City properties, utility runs, site access, and landscape protection can also play a meaningful role. We review your property first, then build a budget around what your project actually requires.
An ADU is a legally defined dwelling unit with its own kitchen and bathroom, permitted under state and local ADU rules. A guest house may or may not include a full kitchen, which changes how it's classified and approved. The right choice depends on how you plan to use the space — family living, guests, staff, or rental flexibility — and we help you understand the implications of each before designing.
When a home needs extensive structural, system, and layout changes, there's a point where rebuilding makes more sense than renovating — and on high-value Redwood City lots, that question comes up often. The answer depends on the home's condition, what you want it to become, and how the numbers compare. Our feasibility process looks at both paths honestly, so you can decide with real information rather than assumptions.