Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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AfterFast, Reliable Home Additions & ADU Across Burlingame
If you’re planning a Home Additions & ADU project in Burlingame, expect to spend between $45,000 and $130,000 for a room addition, and $90,000 to $220,000 for a new detached ADU. That’s the honest range for this market, and we can tell you exactly why: Burlingame sits on bay fill and under SFO’s flight paths, which means geotechnical borings and FAA paperwork that other Peninsula cities never see. The good news is that these aren’t problems you solve after signing. They’re things we scope in writing before you commit a dollar. Call (877) 610-1318 and Tom Barrett will walk you through what applies to your street, not some generic pitch.
Why Barrett & Sons Construction Is Burlingame’s Preferred Home Additions & ADU Company
We’ve been at this since 1998, and the way we work hasn’t changed: every scope, every allowance, every price change arrives as a written change order before work happens. No surprise invoices at the end. That matters more on a $100,000 ADU than on a $500 repair, and Burlingame homeowners who’ve been burned by a national outfit tend to notice the difference immediately.
Tom Barrett publishes his name, his address, and his license number. Look it up before you sign anything. His sons run the crews, and they’re the ones who show up at your house in Burlingame, not a rotating cast of strangers dispatched from a call center. The permit inspector works for you, not for me, which is exactly why we pull permits on every eligible job and get inspections signed off before we call it done.
Our Home Additions & ADU in Burlingame work comes with the 90-Day Done Right Promise written on every contract. If it’s not done right, Tom comes back and makes it right. One call. That’s the whole promise, and it’s been the same since day one.
Our Home Additions & ADU Services in Burlingame
ADU Design & Permitting
Burlingame’s flatland homes near the 94010 ZIP sit on historic bay fill with documented liquefaction risk. Before you draw a single wall, we bring in a geotech for borings and design the foundation to match what’s actually under your lot. That’s not a markup. It’s the difference between a structure that lasts and one that cracks within two wet seasons.
Garage Conversion ADU
A garage conversion in the Easton Addition or Burlingame Park usually runs $30,000 to $80,000, but the FAA Part 77 height cap rarely bites on a single-story conversion. Where it does bite is on second-story work near Broadway or the Bayfront, where SFO’s transitional airspace surfaces clip a surprising amount of the city. We file the Form 7460-1 early so the 45-day review clock doesn’t stall your permits.
New Detached ADU
On acreage parcels in the Burlingame Hills, a detached ADU hits $90,000 to $220,000, and county septic and well setbacks drive a big share of that. You can’t assume standard setbacks apply. We survey the well and leach field before rough-in so the health department’s percolation test doesn’t fail at the worst possible moment. Grading and drainage on a sloped lot get scoped in the same week, not after excavation reveals a problem.
Junior ADU & Interior Conversion
A junior ADU inside an existing Burlingame home is the most budget-friendly route, but the lath-and-plaster walls and knob-and-tube wiring in 1920s Craftsman bungalows add scope. We price the electrical upgrade and wall work honestly up front, so your $45,000 room addition doesn’t become a $70,000 surprise.
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 Burlingame
We install materials you can look up, not mystery brands off a van. For windows and doors on Burlingame additions, we carry Simonton, Ply Gem, and PGT lines, and we can source CGI impact products for bayfront parcels where wind and moisture exposure run higher. We keep local stock moving for Burlingame customers, so a window order for your enclosed patio doesn’t sit in a warehouse for six weeks while your framing waits.
Common Home Additions & ADU Problems We See in Burlingame Homes
- Bay-fill foundations on flatland homes. Homes near Airport Boulevard and Anza Boulevard sit on uncompacted bay mud. A foundation laid without geotechnical borings can crack within two wet seasons, triggering change orders and a failed final inspection.
- FAA 7460-1 obstruction evaluations near the Broadway and Bayfront corridors. SFO’s transitional airspace surfaces clip a significant swath of Burlingame, and the 45-day review clock doesn’t pause for a client’s move-in date. Skipping this filing stalls permits and pushes projects past deadlines.
- Septic and well setbacks on hillside acreage. A detached ADU on a Burlingame Hills parcel can fail the health department’s percolation test if the well and leach field aren’t surveyed before rough-in. Retaining wall reconstruction and subsurface drainage upgrades are standard companions on sloped lots.
- Marine moisture and wood rot. Burlingame’s persistent summer fog accelerates rot in soffits, fascia, and subfloor framing faster than inland Peninsula cities at the same latitude. When we open walls on a 1930s Spanish Colonial Revival, we plan for rot repair in the allowance, not as a surprise change order.
Pricing for Home Additions & ADU in Burlingame, CA
Here’s what you can expect to pay in Burlingame right now. These are line-item ranges, not vague guesses:
| Project | Typical Burlingame Range |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
What moves the number: lot conditions (bay fill vs. hillside), septic and well setback compliance on acreage, FAA filings for anything near flight corridors, and whether your addition triggers a seismic retrofit on an older foundation. We scope all of it before quoting, and every change after that comes as a written change order. Call (877) 610-1318 for a free estimate, and we’ll put every number on paper.
We Also Serve Cities Near Burlingame
Our crews work throughout the mid-Peninsula. In addition to Burlingame, we serve Hillsborough, Millbrae, San Mateo, and San Bruno. If you’re a few minutes north or south of the Burlingame border, the same Home Additions & ADU team handles your estimate and your build.
Serving Burlingame, CA - Our Local Coverage Area
We’re based in the Burlingame 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 - Home Additions & ADU in Burlingame
No, a single-story detached ADU typically falls below the height threshold that triggers a Form 7460-1 filing, but the answer changes fast if the unit sits on a raised foundation or a hillside ridge that pokes into SFO’s transitional airspace. We check the specific coordinates of your parcel against Part 77 surfaces before we quote, so you don’t get blindsided by a 45-day review clock. Call (877) 610-1318 for an exact answer on your lot.
Setbacks add anywhere from a few thousand to tens of thousands, depending on whether the health department requires a variance for your leach field or a relocated well. On Burlingame Hills parcels, we’ve seen percolation tests fail when the well and leach field weren’t surveyed before rough-in, forcing a redesign that no change order should ever surprise you with. We survey first and price it in writing. Call (877) 610-1318 to get your lot evaluated.
Burlingame Hills lots shed winter rainfall fast, and sloped ground concentrates runoff against the downhill side of any structure. A second story adds roof area and downspout volume, which means the hillside below needs engineered retention and drainage or the foundation gets undermined. We design both in the same scope because one without the other fails within a few wet seasons. Call (877) 610-1318 for a site walk and a written scope.
For a true single-story garage conversion, almost nothing. The Part 77 cap becomes binding when you add a second story or a roof deck, and the Easton Addition’s proximity to SFO’s approach corridors means some parcels there face height limits lower than what San Mateo or San Carlos would ever require. If your conversion stays single-story, you’re fine. If you’re dreaming of a rooftop terrace, call (877) 610-1318 and we’ll check your parcel before you fall in love with a plan that can’t get permitted.
Keeping the same footprint helps, but any new foundation work on bay fill within the 94010 ZIP still triggers geotechnical review under current Burlingame building codes. You can’t pave over a liquefaction risk with good intentions. We bring in the geotech, run the borings, and design an engineered foundation that satisfies the inspector, which is the person who actually signs off your project. Call (877) 610-1318 and we’ll tell you what applies before you commit.
Building on Burlingame Acreage: What Actually Changes the Price
Burlingame isn’t one market. It’s two. The flatland homes near Broadway, Easton Addition, and Burlingame Park sit on historic bay fill, and the hillside parcels above El Camino Real rise into SFO’s airspace and slope steep enough to test any foundation. A Home Addition on a flatland lot near Airport Boulevard means geotechnical borings first. Always. A New Detached ADU on a Burlingame Hills acreage parcel means county septic and well setbacks, grading and drainage, and likely an FAA Form 7460-1 filing if the ridge line clips the transitional surface.
On a recent Burlingame Hills mid-century ranch with a sloped lot, our crew scoped a New Detached ADU where the county required a septic setback variance and a 45-day FAA Form 7460-1 filing due to SFO’s transitional airspace clipping the ridge. We brought in a geotech for borings, designed a pier-and-grade-beam foundation to handle the runoff, and wrote the draw schedule to release payments only after the inspection sign-off on the rough-in and subfloor. That’s what scoping a hillside ADU in Burlingame actually looks like.
The allowance that isn’t on paper is a surprise waiting for a date. On Burlingame projects, we put the geotech line, the FAA filing line, the septic survey line, and the drainage line on the estimate as named items with dollar figures. If the health department comes back with a setback variance requirement, you’ll see it as a written change order with a number attached, not a phone call apologizing for the overage.
One more thing about Burlingame specifically: out-of-area general contractors pulling permits for anything multi-story near the Broadway or Bayfront corridors are routinely caught off guard by the FAA notification requirement. SFO’s transitional airspace surfaces clip a significant swath of Burlingame, and the 45-day FAA review clock doesn’t pause for a client’s grand opening date. We’ve been through it enough times to file early, track the review, and build the timeline around the actual approval, not the one you hoped for.
If you’re ready to put real numbers on your addition or ADU, call (877) 610-1318. We’ll walk your lot, check the airspace and the soil report, and hand you a written estimate with every line item accounted for. Free. No trip charge inside the county.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Burlingame since 1998.