Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
Before
After
Before
After
Before
AfterFast, Reliable Home Additions & ADU Across Burlingame
Adding square footage in Burlingame is rarely a simple bump-out. Between the FAA airspace rules that shadow the El Camino Real corridor, the bay-fill soils near Airport Boulevard, and the sloped lots up in Burlingame Hills, a home addition or ADU here comes with permitting layers and soil conditions you will not find in San Mateo or Millbrae. Our Home Additions & ADU team has walked through enough Burlingame plan checks to know which questions get asked twice.
We have been building on the Peninsula since 1998, and the way we scope a Burlingame project starts with what is under the dirt and what is in the air above the roofline. Call (877) 610-1318 and we will come look at your lot before we put a single number on paper.
Why Barrett & Sons Construction Is Burlingame’s Preferred Home Additions & ADU Company
Tom Barrett founded this company in 1998, and his sons run crews in Burlingame every week. That matters when the job is a second-story addition off Broadway and the city planner asks who is pulling the permit. It is our name on the form, not a subcontractor you will never see again. Tom lives twenty minutes away. If something is not right, he wants to know about it.
Burlingame homeowners have watched out-of-area contractors quote a garage conversion, then stall for two months because they did not know an FAA Form 7460-1 was required. We file that paperwork as part of our upfront scope, not as a surprise change order. Every price adjustment arrives in writing before work moves. Every permit gets pulled, every inspection gets signed, and every job carries the 90-Day Done Right Promise. If it is not done right, one call brings Tom back.
We also keep things neighborly. A live person answers our phone 24/7, not a voicemail box. You will not get routed through a call center in another state. You will get one of us, usually within a ring or two.
Our Home Additions & ADU Services in Burlingame
ADU Site Prep & Utilities
Site prep drives more hidden cost on Burlingame ADUs than any other line item. On the flatland lots east of El Camino, we often hit historic bay fill that needs geotechnical borings before the foundation design is even drafted. Up in the hills, slope stabilization and drainage come first, or your new ADU becomes a retaining-wall repair project within two winters. We scope sewer laterals, water service, electrical service capacity, and grading in the first quote, not the third change order.
New Detached ADU
A detached ADU in Burlingame typically runs $90,000 to $220,000 depending on site conditions, foundation type, and finish level. On a flat Easton Addition lot with decent soil, you are looking at the lower end of that range for a simple one-bedroom unit. On a Burlingame Hills slope that needs retaining-wall reconstruction and pier-and-grade-beam foundations, the number climbs fast. We quote it honestly, with every allowance in writing before you sign.
Garage Conversion ADU
Converting an attached garage in the 94010 zip is usually the most cost-efficient path to rental income or in-law housing, running $30,000 to $80,000 in Burlingame. But the older the home, the more likely the garage slab lacks a proper vapor barrier and the walls have open stud cavities never meant for living space. We inspect the existing framing and foundation first, then tell you what stays and what gets rebuilt.
Room Additions
A room addition in Burlingame runs $45,000 to $130,000. The spread comes down to foundation conditions, roofline tie-in complexity, and whether the addition triggers seismic upgrades to the existing structure. Homes from the 1920s and 30s in Burlingame Park and the Easton Addition often lack anchor bolts, and any addition above 500 square feet will bring the whole house into current lateral-load code. We plan for that from day one so the inspector does not flag it at final sign-off.
What happens when you call
- 1
A real person answersNo phone trees - you reach a local pro.
- 2
You get an upfront price rangeHonest numbers before anyone is dispatched.
- 3
A background-checked tech heads outLicensed & insured, dispatched right away.
- 4
You approve before work beginsNothing starts until you say go.
Trusted Brands We Service in Burlingame
We install materials you can look up before you hire us. On Burlingame ADUs and additions, we routinely frame with window and door packages from Simonton and Ply Gem, and we spec glazing that holds up to the marine moisture that rolls in off the bay every summer. We also keep a running relationship with local Burlingame suppliers, which shortens lead times on everything from framing lumber to finish hardware. No mystery brands off a van, no specs we will not put in writing.
Common Home Additions & ADU Problems We See in Burlingame Homes
- FAA airspace surprises on multi-story work: Any addition over a certain height along El Camino Real or near the bayfront must clear a federal obstruction evaluation under Part 77. We have watched projects sit with a stack of lumber on site for 45 days because the contract left the 7460-1 filing out of the scope. We file it first.
- Hillside drainage undermining foundations: On sloped Burlingame Hills lots, winter runoff concentrates against the new foundation line. If the drainage plan is an afterthought, the subfloor framing starts wicking moisture and the county eventually red-tags the retaining wall. We build drainage and slope stabilization into the original scope.
- Bay-fill soil on flatland parcels: Near Airport Boulevard and Anza Boulevard, what looks like a standard flat lot is actually historic bay fill with documented liquefaction risk. A standard concrete perimeter foundation will crack within years. Engineered foundations and geotechnical borings are not optional here.
- Seismic retrofit surprises in older homes: The Craftsman bungalows and Spanish Colonial homes in Burlingame Park and the Easton Addition often have original concrete perimeter foundations without modern anchor bolts. Any substantial room addition triggers lateral-load requirements that bring the existing house into code. A contractor who does not plan for that will drop a five-figure change order mid-project.
Pricing for Home Additions & ADU in Burlingame, CA
Here are the broad ranges we quote for Burlingame work:
| Project Type | Typical Burlingame Range |
|---|---|
| New Detached ADU | $90,000 - $220,000 |
| Room Addition | $45,000 - $130,000 |
| Garage Conversion ADU | $30,000 - $80,000 |
What shifts the number is rarely the square footage alone. A sloped lot in Burlingame Hills with retaining-wall work and pier foundations will land at the top of the range. A flat Easton Addition lot with decent soil and a straightforward roofline tie-in will land lower. Before we quote, we walk the land, check the soil report if one exists, review the FAA surface map for your parcel, and put every allowance on paper. Then the quote stays the quote unless you change the scope. And if you have a written estimate from another company, we will give you a free second opinion. Call (877) 610-1318 to schedule your free estimate.
We Also Serve Cities Near Burlingame
Home Additions & ADU in Burlingame sits at the center of our Peninsula coverage. We work across Hillsborough, Millbrae, San Mateo, and San Bruno, and we understand the permitting differences between each city. If you own property in a neighboring town, call us and we will tell you what changes.
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
Yes. Flatland lots near Airport Boulevard and Anza Boulevard sit on historic bay fill with documented seismic liquefaction risk, which triggers geotechnical borings and engineered foundation requirements before the city will issue a building permit. You may also need the FAA Form 7460-1 obstruction evaluation if your structure is tall enough to penetrate Part 77 airspace surfaces tied to SFO’s approach corridors. The 45-day federal review clock runs separately from city plan check, so we file early. Call (877) 610-1318 and we will check your parcel’s airspace and soil status before you spend a dollar on plans.
Any second-story addition along the El Camino Real corridor that reaches into SFO’s transitional airspace must clear a Form 7460-1 obstruction evaluation before construction, which typically adds 45 or more days to the permitting timeline. The FAA review does not pause for your opening date, and missing it will leave you with a stack of lumber and a stop-work risk. We pull the Part 77 surface map for your parcel during our first site visit so the federal filing is in the original scope of work, not a change order. Call (877) 610-1318 for a free estimate that includes the federal layer.
Almost certainly not. Homes in the Easton Addition are dominated by 1920s to 1940s structures, most with original concrete perimeter foundations that lack modern anchor bolts. Converting an attached garage into living space triggers lateral-load code requirements that apply to the existing house, not just the new ADU. You will need a structural engineer to evaluate the foundation and likely a retrofit before the building official signs off. We plan for that from the first site visit so the seismic work appears in the upfront scope, not as a surprise line item. Call (877) 610-1318 and we will walk your garage with you before quoting.
Retaining-wall reconstruction and subsurface drainage. On a sloped Burlingame Hills lot, we had to rebuild a failing retaining wall before we could even stake the ADU foundation, because decades of runoff from the original mid-century ranch had been undermining the slope. We added subsurface drainage and switched to a pier-and-grade-beam design to keep the septic setback clear. That hillside prep was in our scope from day one, and the county inspected the wall and drainage before we poured. A contractor who skips that prep will be back in two winters with a red-tagged wall. Call (877) 610-1318 and we will walk your slope with you.
Yes. Burlingame issues its own building permits through the city, not the county, and any structural addition requires a permit regardless of square footage. The 500-square-foot threshold is a common misconception, but in Burlingame even a small bump-out triggers plan check, which also means the existing structure gets reviewed for seismic compliance. We pull permits on every eligible job, and we do not treat permits as optional the way some contractors do. The permit inspector works for you, not for me. Call (877) 610-1318 and we will tell you exactly what your specific addition will need.
Key Takeaways
- Burlingame additions and ADUs face FAA Part 77 airspace review along El Camino Real and the bayfront, which can add 45+ days to your timeline.
- Bay-fill soils near Airport Boulevard require geotechnical borings and engineered foundations, not standard concrete perimeters.
- Burlingame Hills sloped lots need retaining-wall and drainage work priced into the ADU scope before the quote is final.
- We scope every allowance, every permit, every FAA filing, and every seismic retrofit in writing before work starts.
- Call (877) 610-1318 to schedule a free estimate on your Burlingame project.
Contact Barrett & Sons Construction in Burlingame
If you are thinking about a home addition or ADU in the 94010 or 94011 zip, start with a site visit, not a phone quote. We will walk your lot, check the FAA airspace map, review the soil conditions, and tell you what the project actually needs before we hand you a number. Then the number stays the number unless you change the scope, in writing, first. Call (877) 610-1318 to schedule your free estimate.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Burlingame since 1998.