A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateFast, Reliable Home Addition Contractor Across San Bruno
Adding square footage to a San Bruno home usually costs between $250 and $450 per square foot for a standard attached addition, with most full room additions landing in the $90,000 to $220,000 range depending on scope, foundation work, and the kind of permitting your specific lot requires. If you’re on a standard city lot, that’s one set of rules. If you’re on one of San Bruno’s unincorporated acreage pockets, it’s a different rulebook entirely. We know both. Call (707) 760-0502 and we’ll walk you through exactly what applies to your property, in plain English, with a written price before anything gets built.
We’re Lodgewick ADU Builders, the ADU and home addition company of the Kingswell family. Our Home Addition Contractor team serves homeowners across San Bruno, from the hillside streets off Sneath Lane down to the flatlands near San Bruno Avenue. Russ Delmar leads our crew, and every project we run operates under The Kingswell Guarantee: a written price first, a real arrival window, a clean job site, and a written guarantee on every job.
Why Lodgewick ADU San Francisco Is San Bruno’s Preferred Home Addition Contractor Company
San Bruno homeowners don’t need a contractor who’s guessing. They need someone who has actually walked lots near Crestmoor and Portola Highlands, measured septic clearances on the unincorporated edges, and quoted second-story additions over 1950s ranches with original foundations. That’s the work we do every week. Russ Delmar has built our reputation in San Bruno on one habit: we say the price before the work starts, and we put it in writing. No price changes at the door. No “we’ll figure it out when we open the wall.”
Every technician on a San Bruno job is background-checked and wears a uniform. You’ll know exactly who is on your property, and when they’re arriving. Our crews work on schedule, show up in the window we give you, and leave the job site cleaner than they found it. That’s The Kingswell Way. If something isn’t right, the 365-Day Done Right Promise means we come back and make it right. That commitment is on paper, on every single project.
One thing homeowners tell us after working with other contractors: the worst part was never knowing what anything would cost. We don’t work that way. You get a written price before any work begins. Always. Every project. No exceptions. And a live person answers our phone 24 hours a day, seven days a week. No voicemail loops when you have a question about your build.
Second Story Addition Contractor in San Bruno
A Second Story Addition Contractor in San Bruno has to think about things a first-floor addition never raises. Many San Bruno homes were built between the 1940s and 1970s, which means the existing foundation was never engineered to carry a second floor. Before we quote a second-story addition over a ranch-style home in the Rollingwood or Crestmoor areas, we walk the property and check the foundation type, the floor joist spacing, and what’s under the house. On some 1950s ranches, the footings are fine. On others, they need reinforcement, and that changes the price materially.
A second-story addition in San Bruno typically runs $300 to $500 per square foot, or roughly $180,000 to $350,000 for a standard 600 to 700 sq ft build. The wide range isn’t padding; it’s the difference between a straightforward vertical addition over a newer foundation and a project on a hillside lot with a narrow driveway, a septic system to work around, and a crane pickup that has to be coordinated days in advance.
Foundation and Septic Setbacks
The single most common surprise on a San Bruno second-story addition is a septic clearance violation. On larger lots, particularly near the unincorporated edge off Sneath Lane and in the Portola Highlands, the county has its own setback rules. A second-story addition that is perfectly legal under city zoning can get flagged by the county because a corner of the new footprint is 42 feet from a leach field instead of the required 50. We measure these things before we quote.
Fog, Moisture, and Building Envelope
San Bruno’s fog is not a background detail. It’s a moisture load. Any second-story addition here needs a properly spec’d vapor barrier and insulation that can handle damp, cool conditions year-round. We have seen additions built by other contractors develop mold inside the first winter because the envelope was spec’d for a drier climate. We don’t let that happen. Moisture-resistant materials and exterior-grade sheathing are standard on our San Bruno builds, not an upgrade.
Garage Addition Contractors in San Bruno
Garage Addition Contractors in San Bruno work on two kinds of projects: converting an existing garage into living space, or building a new attached or detached garage structure with finished space above or beside it. On standard city lots, which in San Bruno are often a modest 5,000 to 7,000 sq ft, the second kind of project is more common than you’d think. Many homeowners in the Mills Park and Crystal Springs neighborhoods can’t legally build a detached ADU at all because of a historic prohibition on new ADUs in those specific areas, which is why some turn to ADU Builders in San Bruno to explore permitted alternatives. But a garage addition, particularly a conversion of an existing structure, is often a different permitting path entirely.
A garage conversion in San Bruno typically runs $180 to $350 per square foot, or about $80,000 to $160,000 for a standard two-car garage turned into a bedroom suite, office, or family room. A new detached garage with a finished loft or workshop space above runs higher: $250 to $400 per square foot, depending on whether foundation, drainage, and electrical service need upgrades.
Why the Original Foundation Matters
Many San Bruno garages sit on slabs or minimal footings that were never designed for habitable space. Before you convert a garage, the floor may need to be raised or insulated, the slab may need a moisture barrier, and the ceiling will almost certainly need structural work if you’re adding a second level. We inspect all of this before quoting, and the written price covers it. You’ll know what the real scope is before you commit.
On Larger Lots, Detached Becomes Practical
On San Bruno’s larger parcels, a detached garage addition starts to look like a small house. We’ve scoped several projects where a detached two-car garage with a finished 400 sq ft workshop or office above made more sense than adding onto the main structure. On acreage lots, this kind of addition doesn’t compete for space with a septic system or a well the same way an attached build does, and it can be sited specifically to keep county setback clearances clean.
Trusted Brands We Service in San Bruno
Homeowners in San Bruno often ask us about prefab and panelized options from Abodu, Cover, and Tuff Shed. We work with these manufacturers directly, matching each homeowner’s lot, budget, and timeline to the right system. On a tight city lot, a panelized build from Abodu can cut framing time significantly. On a hillside parcel with difficult access, we have used Tuff Shed’s engineered structures as the core of a permitted workshop or studio addition. For exteriors, we stock and install James Hardie plank siding, which holds up exceptionally well in San Bruno’s damp, fog-heavy conditions. We stock common materials locally for San Bruno customers, which shortens turnaround when a project needs to move.
Common Home Addition Contractor Problems We See in San Bruno Homes
- City vs. county rule confusion. San Bruno sits across a patchwork of city and unincorporated parcels. We’ve seen additions scoped under city setback rules get flagged by the county because a septic line clearance violation only appears on the county’s rulebook. The fix is knowing which jurisdiction actually governs your lot before the first drawing is made.
- Fog-driven moisture issues. A new addition in San Bruno that isn’t built with a proper vapor barrier and correctly spec’d insulation will develop condensation inside the walls during the first winter. The fog off the Pacific isn’t occasional; it’s a daily moisture source from June through August and a persistent dampness the rest of the year.
- Hillside and access challenges. Many San Bruno homes sit on hillsides with narrow, winding driveways. A standard quote for a second-story addition doesn’t account for the crane and material haul logistics of a 40-foot delivery truck that can’t make the turn. We map driveway turning radius before we quote on these lots.
- Older foundations and electrical systems. A house built in 1955 with a good interior may still have an original foundation and a 100-amp electrical panel. Any addition that adds a bathroom, kitchenette, or heavy electrical load will require a panel upgrade. We identify that requirement during the quoting process, not as a change order after demo starts.
Pricing for Home Addition Contractor in San Bruno, CA
Here are the honest numbers for San Bruno. A standard attached room addition runs $250 to $450 per square foot. A second-story addition runs $300 to $500 per square foot. A garage conversion runs $180 to $350 per square foot. A new detached garage or workshop with finished space runs $250 to $400 per square foot. A small bump-out, like extending a kitchen by 6 to 8 feet, runs $60,000 to $110,000. A sunroom addition runs $60,000 to $140,000 depending on glazing and whether you want it conditioned for year-round use.
What moves the price on a San Bruno project more than anything is the lot itself: septic and well setbacks, hillside access, foundation condition, and whether you’re under city or county jurisdiction. We scope all of that before we quote. Call (707) 760-0502 and we’ll walk your specific property, measure what needs measuring, and give you a written line-item price. The estimate is free.
We Also Serve Cities Near San Bruno
Our crews work throughout the northern Peninsula, including nearby Home Addition Contractor in San Bruno neighbors: Millbrae, Daly City, San Francisco, and San Carlos. If your property sits close to a city boundary, we can tell you quickly which jurisdiction’s setback rules apply. Scheduling is coordinated from our San Francisco Bay Area office, with crews dispatched locally to San Bruno job sites.
Serving San Bruno, CA - Our Local Coverage Area
We’re based in the San Bruno area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs About Home Addition Contractor in San Bruno
It depends on whether your parcel is inside San Bruno city limits or in one of the unincorporated pockets nearby. In the unincorporated areas, San Mateo County handles permitting, and the county has its own septic setback, well clearance, and grading rules that differ from city standards. Sometimes both rulebooks apply on the same street. We determine which jurisdiction applies to your parcel before we quote, so there are no surprises mid-project. Call (707) 760-0502 and we’ll check your specific lot.
Usually not, but it depends on what’s under the house. Some 1950s ranches in San Bruno were built with footings that can carry a light second story with reinforcing. Many were not. We inspect the foundation, joist spacing, and existing load paths before quoting, and the written price includes whatever reinforcement is actually needed. No change orders after demo. Call (707) 760-0502 for a foundation check.
If the county is the permitting authority and your new addition footprint is within 50 feet of a septic tank or leach field, the addition will likely be flagged during plan review. The fix is often a redesigned footprint, a different foundation type, or in some cases a septic system upgrade. This is exactly the kind of problem we catch before quoting, not after. Call (707) 760-0502 and we’ll measure the clearances on your lot.
San Bruno’s maritime climate means cool, damp air for a large part of the year. A properly built addition here needs a vapor barrier, correct insulation values for a moist climate, and exterior materials that don’t retain water. We’ve seen additions by other contractors develop mold before the first winter ends because the envelope was under-spec’d. Our standard San Bruno builds include the right moisture control from day one. Call (707) 760-0502 to talk about your project.
You can build a detached structure as a workshop, office, studio, or storage space, and it does not have to meet ADU requirements if it has no kitchen and no full bathroom. The setback, height, and lot-coverage rules still apply, and they differ between city and county jurisdictions. On larger San Bruno lots, we’ve designed detached workshops with finished upper floors that avoid the ADU rulebook entirely while still adding real usable square footage. Call (707) 760-0502 and we’ll tell you what’s allowed on your lot.
Call for a Free Estimate in San Bruno
If you’re planning a home addition in San Bruno and want a real number in writing, call (707) 760-0502. We’ll walk your property, measure the setbacks, check the foundation, map the access, and give you a written price before any work begins. Russ Delmar and the Lodgewick team serve San Bruno home and acreage lots alike, and every project comes with The Kingswell Guarantee and the 365-Day Done Right Promise in writing. Call today.
Written by Russ Delmar, Owner at Lodgewick ADU San Francisco.
