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 Daly City
Adding square footage to a Daly City home usually lands somewhere between $45,000 and $130,000 for a room addition, and $90,000 to $220,000 for a full detached ADU. Those numbers don’t jump around much once you know what’s behind the walls of a Doelger-era house. We’re Barrett & Sons Construction, and we’ve been opening up Daly City homes long enough to know exactly what’s back there before the first hammer swings. If you’re planning an addition or ADU anywhere from Westlake to the 94015 corridor, call (877) 610-1318 and we’ll walk your property and give you a written, line-by-line estimate.
What sets a Daly City project apart from the rest of the Peninsula is the housing stock itself. We’ll get into that below, because it changes what your quote actually needs to include.
Why Barrett & Sons Construction Is Daly City’s Preferred Home Additions & ADU Company
Tom Barrett founded this company in 1998, and his sons run the crews. We’re not a franchise dispatching strangers to your door. When you call about a Home Additions & ADU project in Daly City, you’re talking to the people who will actually stand in your living room and explain what the permit inspector will be looking for. Tom publishes his name, his address, and his license number. Look it up before you sign anything. We’d rather you did.
Daly City homeowners call us because we answer the phone at midnight and show up when we say we will. We’ve worked blocks in Westlake, St. Francis Heights, and Broadmoor where the same Doelger construction details repeat house after house. That repetition matters. It means when you ask us for a second-story addition quote on a 1954 stucco home in the 94015 ZIP, we already know what the foundation looks like before we step inside. We carry that knowledge from every Daly City job to the next one.
Every contract carries our 90-Day Done Right Promise in writing. If something isn’t right, Tom comes back and makes it right. One call. That’s not a slogan. It’s on every contract we write.
Our Home Additions & ADU Services in Daly City
Second Story Additions
Adding a second story in Daly City is different from doing it in San Mateo or Redwood City. The Doelger homes built between 1949 and 1963 were framed for one level only. The cripple-wall stem foundations under the 94015 and 94014 corridors were never engineered to carry the load of a full upper floor. Before we frame a single wall, we check what’s underneath. Most second-story additions on Doelger-era homes require seismic bracing: anchor bolts into the sill plate, plywood sheathing on the cripple walls, and often a shear wall detail that the city’s building inspector will want to see before we proceed. We write that work into the scope up front, so you’re not surprised when the permit comes back with conditions.
Garage Conversion ADU
Daly City has thousands of tuck-under garages, especially on the sloped blocks of Westlake. This is the classic soft-story configuration, and it’s the single biggest issue in garage conversion ADUs here. You can’t just frame out a garage, run plumbing, and call it a day. The cripple walls carry the weight of the living space above. If they aren’t braced, the city will not sign off, and worse, an unbraced wall can shift in an earthquake. We handle garage conversions in Daly City from $30,000 to $80,000, including the seismic bracing, the drainage, and the utility runs. We pull permits on every one.
New Detached ADU
A standalone ADU in a Daly City backyard runs $90,000 to $220,000 depending on size, foundation type, and utility trenching. The fog is a real factor here. Daly City sits in one of the densest fog belts in the Bay Area, and west-facing elevations take constant marine moisture. Detached ADUs need exterior details that hold up: proper flashing at the roof-to-wall transition, moisture-resistant sheathing, and stucco or siding systems rated for wet exposure. We spec those from day one because we know what happens when you don’t. GAF roofing products are a regular choice for Daly City ADUs for exactly that reason.
Junior ADU & Interior Conversion
A junior ADU, usually carved out of an existing bedroom or finished attic, is the most budget-friendly way to add a rentable unit in Daly City. These projects typically start under $100,000 and move fast because they stay inside the existing envelope. But the older the home, the more likely you’ll hit electrical that was never built for a kitchenette or a separate entrance. Original Doelger wiring was 60-amp service in many cases. Adding a cooking surface and a bathroom can trigger a panel upgrade. We include that in the written allowance so you know what’s coming. Nothing gets added without your signature on a change order.
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 Daly City
We install materials you can look up by name. On Daly City ADU and addition projects, we regularly use Schluter waterproofing systems in kitchens and wet areas, Sterling fixtures where durability matters, and GAF roofing products on any new roof surfaces. We don’t stock mystery brands off a van. The 90-Day Done Right Promise backs the installation, and the manufacturer warranty backs the product. If you’re in Daly City and want to know what’s going into your walls, ask us. We’ll tell you, and it’ll be in writing.
Common Home Additions & ADU Problems We See in Daly City Homes
- Unreinforced cripple-wall foundations. Nearly every Doelger home built before 1963 has a stem wall foundation with no anchor bolts. Add a second story or convert a tuck-under garage, and the city requires seismic bracing before sign-off. This is the single most common reason a Daly City addition quote changes during permitting.
- Fog-driven stucco delamination. West-facing elevations in the 94015 and 94014 ZIPs take persistent marine moisture. Stucco pulls away from the lath, eave soffits rot, and mold creeps into the wall cavity. Adding on means tying into the existing envelope, and if that envelope is failing, the inspector will flag it.
- Soft-story garage conditions. On sloped Westlake blocks, the garage sits under the living space with minimal lateral support. Converting that garage to an ADU without addressing the soft-story issue is a recurring failure mode. We brace it before we frame it.
- Outdated 60-amp electrical service. Doelger-era homes were built for a different electrical load. Adding a kitchen, a bathroom, or a laundry hookup often trips the panel. We write the panel upgrade into the allowance so it’s on paper before it’s on your bill.
Pricing for Home Additions & ADU in Daly City, CA
Here’s what we’re seeing across Daly City right now. These are real ranges tied to the scope, not phone quotes designed to get a foot in the door:
| Project Type | Typical Daly City Price Range |
|---|---|
| Garage Conversion ADU | $30,000 - $80,000 |
| Second Story Addition | $45,000 - $130,000 |
| ADU Construction (new detached) | $90,000 - $220,000 |
What moves the number in Daly City is almost always the hidden condition underneath. Cripple-wall bracing, rim joist replacement, panel upgrades, stucco repairs at the tie-in. We inspect, we write the allowance into the contract, and if something shows up after we open the wall, it comes to you as a written change order with a price before we touch it. The allowance that isn’t on paper is a surprise waiting for a date. We don’t do that. Call (877) 610-1318 for a free written estimate, and we’ll price your addition or ADU in Daly City based on what’s actually there.
We Also Serve Cities Near Daly City
Our crews work all over the northern Peninsula. If you’re not in Daly City proper, we also serve Visitacion Valley, South San Francisco, Noe Valley, and the Mission District. Wherever you are, the same rule applies: written scope, written allowances, and permits pulled on every eligible job. If you’re inside the county, there’s no trip charge to come look.
Serving Daly City, CA - Our Local Coverage Area
We’re based in the Daly City 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 Daly City
Opening a 1950s Doelger home usually uncovers two things that change the quote: unreinforced cripple walls and hidden rot at the stucco-to-roof transition. The seismic bracing alone typically adds thousands to the final number because the city requires it before inspection sign-off. That’s why we write a foundation allowance into every Daly City addition contract, so the number you sign on day one already accounts for what we expect to find. Call (877) 610-1318 and we’ll walk your home and show you what the allowance covers.
Yes, in virtually every case on the sloped blocks of Westlake and the surrounding 94015/94014 corridors. The tuck-under garage creates a soft-story condition, and the city will not issue final sign-off on an ADU conversion unless the cripple walls are braced with anchor bolts and plywood sheathing. We include the retrofit in the garage conversion scope from the start, not as an afterthought once the inspector shows up.
Daly City sits in a fog belt that pushes marine moisture against west-facing elevations for months at a time. The original Doelger stucco-over-lath system was never detailed for that kind of sustained wet exposure, so decades of fog have caused delamination and rot at the eave lines. When we tie a new addition into an existing wall, we check the transition first. If the stucco is failing, we write the repair into the change order before we connect the new framing. The permit inspector works for you, not for me. That’s why I like him.
In many Daly City Doelger homes, yes, if the existing stem wall is intact. We can often brace the cripple walls with anchor bolts and plywood sheathing rather than replacing the foundation entirely. But some of these homes have rim joists so rotted from fog-driven moisture that the under-floor framing won’t carry the new load, and that’s when a partial foundation repair has to be written in. We won’t know for certain until we open the wall. What we will do is put the allowance on paper before we open anything, so you approve the fix, in writing, before it happens.
A change order is the written document that lists what was found, what it costs to fix, and what you’re approving before we proceed. On a Daly City ADU, a typical change order covers things like a rotted rim joist, a panel upgrade, or additional seismic bracing the inspector flagged during the rough inspection. You sign it before we spend a dollar on it. If it isn’t on paper, it doesn’t happen, and you don’t pay for it. That’s how we’ve worked since 1998, and it’s how we’ll work on your Daly City project. Call (877) 610-1318 for a free estimate.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Daly City since 1998.