Fast, Reliable Garage Conversion ADU Across San Bruno
Garage conversion ADUs in San Bruno typically run $180,000-$340,000 all-in, drawings through final inspection, depending on whether you’re converting an attached garage, a detached structure, or adding a full bathroom and partition. Most San Bruno conversions take 9-14 months from design start to certificate of occupancy, with the permit set alone consuming 4-6 months under the city’s current planning review load. We’ve designed, permitted, and built garage conversions in San Bruno neighborhoods from Crestmoor to Portola Highlands, and we know where the airport noise contours, the salt fog, and the city’s utility requirements intersect with your specific lot. Call (971) 497-2402 and we’ll walk you through what your garage can actually become, with a written price before any work starts.
San Bruno’s housing stock is overwhelmingly post-WWII ranch and minimal-traditional homes, most built between 1948 and 1965. These homes were framed when a garage was a garage: uninsulated walls, a slab poured without vapor barrier, and a 60-amp subpanel that was never meant to feed a heat pump. The good news is the bones are usually sound. The bad news is none of the systems are ready for habitation. That’s the work we do, and we do it under one contract at one written price, so the designer who draws the permit set and the crew who frames the walls answer to the same person: you.
Why Ellery ADU Studio Is San Bruno’s Preferred Garage Conversion ADU Company
Ellery ADU Studio has operated as a design-build studio since 2015, the year California’s ADU permitting landscape shifted and garage conversions became genuinely feasible for ordinary homeowners. We’re not a general contractor who subs out the drawings to a third party. The permit set, the structural engineering, the Title 24 energy model, and the construction are a single contract at a single written price. Under Haven Standard Clause 1, every project begins with a written price before any work starts, and under Clause 5, that scope is locked at signing. No door-side upsells, no designer-versus-builder blame gap.
Nadia Ellery leads the studio, and she reviews every San Bruno garage conversion permit set personally before it goes to the city. That matters because San Bruno’s Planning Division has specific requirements for garage conversions that differ from neighboring cities: setbacks, lot coverage, parking replacement, and increasingly, sound attenuation under SFO’s Part 150 noise contours. A permit set that passes in South San Francisco can get bounced in San Bruno for missing acoustic glazing specs or the wrong ventilation system. We’ve been through that review enough times to know what gets approved the first time.
We’ve designed and permitted over 900 ADUs across the Bay Area since 2015, every one with a written price before work started and a documented photo record when work was complete. For San Bruno specifically, our crews know the western hillside lots where fog sits until noon and the flatter airport-adjacent blocks where arrival noise is a daily fact. That’s not a slogan. It’s what lets us write a scope that doesn’t need six change orders.
Our Garage Conversion ADU Services in San Bruno
Detached Garage Conversion
Detached garages are the most common ADU candidate in San Bruno, especially in the post-WWII tracts where a two-car garage sits at the back of a 5,000-6,500 sq ft lot. But a detached garage conversion in San Bruno has to solve for real problems: the slab’s moisture profile, the uninsulated roof assembly, and in the western hills, unsealed truss joints that funnel marine wind and jet noise into the living space. We specify a tight thermal envelope and sealed mechanical ventilation as standard here, not as an upgrade. Under the San Bruno Gap’s persistent wind, operable windows don’t keep a new ADU comfortable; an ERV does.
Attached Garage Conversion
Attached conversions in San Bruno’s ranch homes often share a roofline with the main house, which means SFO’s Community Noise Insulation Program may have already upgraded the primary dwelling’s windows and HVAC, while the garage still has its original single-pane wood sash. That’s the single most common discovery on our San Bruno attached conversions: the main house is quiet, the new ADU is not. We specify laminated acoustic glazing in marine-grade aluminum frames when the site falls inside the Part 150 contour, and we factor that line item into the written price from day one. If your neighborhood received the airport retrofit, your ADU needs the same treatment.
Garage Partition & Bathroom Add
A partition conversion splits the existing garage footprint into a living unit plus a smaller storage or workshop area, or creates a separate one-bedroom layout with a full bath. In San Bruno, this is where the plumbing realties hit hardest. Most 1950s homes here have aging galvanized or cast-iron laterals, and adding a shower, lav, and kitchen sink often triggers a lateral replacement or lining before the city will final the permit. We inspect the lateral condition during the feasibility walk, name the cost in the written price, and the sewer line work goes into the same contract as the framing and drywall.
Garage JADU
San Bruno’s zoning code, like most San Mateo County cities now, permits Junior ADUs of up to 500 sq ft within an existing structure, including a converted garage. A JADU is the lean version of a Garage Conversion ADU: efficiency kitchen, maybe a shared laundry connection, no separate utility metering requirement in most cases. For San Bruno homeowners weighing a rental under the airport flight path, the JADU economics can be compelling: lower construction cost, faster permit review, and the same sound-attenuation requirements apply so the unit stays rentable.
What happens when you call
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A real person answersNo phone trees - you reach a local pro.
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You get an upfront price rangeHonest numbers before anyone is dispatched.
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A background-checked tech heads outLicensed & insured, dispatched right away.
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You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in San Bruno
We specify and coordinate prefab and modular systems from manufacturers including Abodu, Cover, and Dvele, and we build with James Hardie siding and trim when the coastal fog and salt air demand a cladding that won’t cup or delaminate. Prefab can be the right answer for a San Bruno garage conversion when the existing framing is too compromised to retrofit economically, or when the site access through a narrow Portola Highlands street makes traditional stick-framing logistics expensive. The prefab system gets specified, permitted, and installed under our single contract, so the warranty chain stays clear. If the factory makes a mistake, we fix it. There’s no third party to point at.
Common Garage Conversion ADU Problems We See in San Bruno Homes
We’ve done enough San Bruno garage conversions to know what shows up during demo, and what we specify on the front end to avoid finding it late:
- Unsealed truss joints and plate gaps in hillside garages: the western-facing lots near Crestmoor and Pacific Heights get the full force of the San Bruno Gap’s marine wind. Air moves through those gaps, batt insulation underperforms, and condensation forms on metal fasteners, which then rust. We seal every plate gap and truss intersection before insulation goes in, and we document it in the photo record.
- 60-100A subpanels that can’t carry the ADU load: original San Bruno ranch homes were wired for a garage door opener and a single light fixture. Adding heat-pump HVAC, an electric range, and a water heater trips the panel. The panel upgrade is not optional if the final inspection is going to pass; we name it in the written price, not as a surprise change order.
- Salt-air corrosion on standard galvanized fasteners: in San Bruno’s coastal fog belt, big-box galvanized hardware shows red rust within 18 months, then loosens under wind load. We specify hot-dip galvanized or stainless fasteners and connectors for everything exposed, from roof clips to sill anchors. It costs more on day one and less by year five.
- Single-pane garage windows under the flight path: in the flatter airport-adjacent blocks, the primary home may already have dual-pane retrofit windows from SFO’s noise program. The garage almost never does. The new ADU sits raw under the arrivals corridor, and without laminated acoustic glazing, it’s too loud to rent at market rate. We treat the ADU’s glazing as a compliance item, not an upgrade to sell later.
On a post-WWII ranch near Crestmoor, our crew found the main house’s dual-pane windows quiet thanks to SFO’s retrofit program, but the detached garage’s 1950s single-pane wood sash and unsealed truss joints left a cumulative noise reading over 70 dB during arrivals. We replaced the sash with laminated acoustic glazing in marine-grade aluminum frames, added a sealed ERV for quiet ventilation, and sealed all plate gaps before final. The first night after move-in, the tenant reported sleeping without earplugs.
Pricing for Garage Conversion ADU in San Bruno, CA
Let’s put real numbers on the page. A straightforward attached garage conversion in San Bruno, converting a single-car garage to a studio with a full bath, typically runs $180,000-$230,000, drawings through final inspection. A detached two-car garage conversion with one bedroom, full bath, kitchen, and separate utility runs $240,000-$310,000. A partition conversion with a full bath addition lands between $190,000 and $270,000 depending on the lateral condition and panel situation. A JADU conversion inside an existing garage is typically $130,000-$170,000.
What moves the number in San Bruno specifically: the sound-attenuation package (laminated acoustic glazing, sealed ERV, plate-gap sealing) adds $18,000-$35,000 depending on window count and ceiling area; a 100A to 200A panel upgrade adds $4,000-$7,000; a lateral replacement can add $10,000-$25,000 if the cast iron is done. Every one of those line items gets named in the written price before you sign. Call (971) 497-2402 and we’ll put it in writing for your specific lot.
We Also Serve Cities Near San Bruno
Our crews serve the full San Bruno area and the surrounding Peninsula. We work regularly in San Bruno neighborhoods from Rollingwood to Belle Air, and we also serve South San Francisco, Pacifica, Daly City, and Burlingame. If you’re just over the city line, the permitting authority changes but the approach doesn’t: one contract, one written price, every line item named.
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 - Garage Conversion ADU in San Bruno
Yes, if your property falls inside SFO’s Part 150 noise contours, and roughly the eastern two-thirds of San Bruno does. The noise insulation program that retrofitted your primary home’s windows and HVAC does not extend to the garage, and the city’s current ADU review treats acoustic glazing and sealed ventilation as a livability requirement for new habitable space under the flight path, not as an optional comfort upgrade. Expect to budget $18,000-$35,000 for laminated acoustic glazing, plate-gap sealing, and a sealed ERV on a typical detached conversion. Call (971) 497-2402 and we’ll verify whether your specific lot is inside the contour before we draw the first plan.
Because the San Bruno Gap carries dense marine fog that condenses on metal before the roof ever leaks, and standard galvanized fasteners rust within 18 months in that environment. The rusty fasteners then loosen, and a roof that was fine becomes a roof that moves under wind load and eventually fails at the connections. We specify hot-dip galvanized or stainless fasteners and connectors for all exterior and truss connections on San Bruno conversions as the default, not an upsell. The coastal-spec hardware adds roughly 8-12% to the framing hardware line item and saves you a fastener replacement within a decade.
Almost never. A habitable ADU in San Bruno needs heat-pump HVAC, an electric range or induction cooktop, a water heater, and modern lighting and receptacle loads, and a 60A panel cannot carry that plus the main house. The city will not final an ADU permit with an undersized or borderline panel, and the upgrade to 100A or 200A (usually $4,000-$7,000) belongs in the written price from day one. We don’t surprise you with it at rough-in; it’s a named line item in the scope.
No, not as the primary ventilation strategy. The San Bruno Gap’s persistent marine wind makes operable windows unreliable for comfort: they’re either slammed shut against the wind or left open with fog condensing on every interior surface. We specify a sealed ERV (energy recovery ventilator) as standard on San Bruno ADUs, which brings in filtered air and exhausts stale air without opening the thermal envelope to the wind and jet noise. This is one of the clearest differences between a coastal-spec ADU that stays comfortable year-round and a generic conversion that’s muggy or drafty depending on the day.
Plan on spending $25,000-$45,000 more for a coastal-spec conversion than you would for the same floor plan in an inland Peninsula city. That covers laminated acoustic glazing in marine-grade frames, hot-dip or stainless fasteners and connectors, plate-gap and truss-joint sealing, a sealed ERV instead of operable-window ventilation, and James Hardie siding and trim on any new exterior walls. The inland-spec version of the job looks cheaper on day one, but the first fastener replacement, the first condensation issue inside the wall cavity, and the first tenant complaint about jet noise will absorb that difference. We write the coastal spec into the permit set and the price from the beginning, under Haven Clause 1, because doing it later costs more and means reopening walls.
If you’re weighing a garage conversion ADU in San Bruno, start with the written price. Call (971) 497-2402 and we’ll schedule a feasibility walk on your lot, produce a written price, and give you a Free Second Opinion on any written estimate you already have in hand.
Written by Nadia Ellery, Owner at Ellery ADU Studio, serving San Bruno since 2015.