When your home no longer fits your life, we expand it with precision — second stories, room additions, and ADUs that integrate with the existing structure as if it were always there and the surrounding neighborhood.
A home addition is one of the more complex things a homeowner can take on. You're dealing with structural engineering, layered permitting, and the challenge of tying new space into existing systems — foundation, framing, roofline, mechanical, and the look of the home. It's a lot to coordinate.
Lussoro handles every dimension of this complexity in-house. Our structural and design teams collaborate from day one, ensuring that additions look like they were always there — not something you can tell was added later.
From Our Blog
How Much Does an ADU Cost in San Mateo?
Complete cost breakdown for detached, attached, and garage conversion ADUs.
Design-Build vs. Architect + Contractor: What's the Difference?
Why design-build is especially valuable for additions and ADU projects.
How to Choose a Contractor in the Bay Area
Essential questions and red flags when hiring for your addition project.
Common Questions
Most home additions in San Mateo take 4–8 months from permits to completion, depending on scope. A single-room addition might wrap in 3–4 months, while a second-story addition or ADU typically takes 6–8 months. We build a detailed timeline during the design phase so you know exactly what to expect.
Home additions in San Mateo require building permits, structural engineering approval, and often planning review — especially if you're near setback limits or in a historic area. ADUs have their own streamlined permitting path under California state law. We handle all permit filing, plan submissions, and city inspections as part of our design-build service.
In the Bay Area, home additions typically range from $300–$600+ per square foot depending on complexity, finishes, and whether it's a ground-floor bump-out, second story, or detached ADU. A 400 sq ft room addition might run $150K–$250K, while a full ADU can range from $200K–$400K+. We provide transparent, itemized estimates during your free consultation — no surprises.
Absolutely — that's exactly how we work. As a design-build firm, our architects and builders collaborate from day one, which means fewer miscommunications, faster timelines, and a single point of accountability. You won't need to hire and coordinate separate designers and contractors.
In the Bay Area market, a well-executed addition typically recoups 65–80% of its cost at resale — and ADUs often do even better because of rental income potential. Beyond resale value, you gain livable space that fits your family's needs now. We help you make smart decisions about scope and finishes that maximize both enjoyment and return.
We know you're living in your home during construction, so we plan around that. Our project manager creates a phased schedule, sets clear work hours, and maintains clean, contained work zones. Your dedicated project manager is personally present on every job — so if something comes up, you're talking directly to the person who can fix it.
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