Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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After
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AfterFast, Reliable Home Additions & ADU Across San Pedro
If you’re planning a home addition or ADU in San Pedro, you need a contractor who understands what the salt air off the Pacific and the port do to building materials. We do. A room addition in San Pedro typically runs $45,000-$130,000, and a new detached ADU usually lands between $90,000 and $220,000, depending on whether you’re on a bluff in 90731 or a flatter lot off Gaffey Street. Call us at (877) 610-1318 and we’ll walk your property with you, look at what you’ve got, and give you a written scope with real numbers.
Why Barrett & Sons Construction Is San Pedro’s Preferred Home Additions & ADU Company
We’ve built additions and ADUs on San Pedro’s hillside lots long enough to know where the failures hide. Our crews work regularly in the 90731, 90732, 90733, and 90734 ZIP codes, from the Craftsman bungalows near Point Fermin to the stucco cottages above Harbor Boulevard. When a homeowner in the bluffs above the Port calls about a second-story addition, we already know what the Coastal Commission will ask and what the soil will do. That local knowledge saves you months and thousands.
Tom Barrett puts his name, address, and license number on every contract. He’s not a franchise owner dispatching strangers. His sons run the crews. When you call our office, a live person answers the phone, 24/7. Not a voicemail box. Not an out-of-state call center. If you want to verify who you’re hiring before you sign anything, we’d encourage you to look up the license number yourself. That’s the point of publishing it.
Every San Pedro job comes with permits pulled and inspections signed, a written change order before any scope change, and our 90-Day Done Right Promise written into the contract. If something isn’t done right, Tom comes back and makes it right. One call.
Our Home Additions & ADU Services in San Pedro
ADU Design & Permitting
San Pedro is one of the few places in LA County where a simple ADU permit can turn into a dual-agency process. If your lot sits on the western bluffs in 90731 or 90732, the California Coastal Commission may require a Coastal Development Permit on top of standard LADBS approval. We handle both. Our Home Additions & ADU team has navigated enough CDP reviews in San Pedro to know what triggers them and how to file correctly the first time. That matters because an out-of-area crew that misses the CDP requirement can add months to your timeline after you’ve already budgeted for a spring start.
Garage Conversion ADU
Many San Pedro garages from the 1920s and 1930s were never built to become living space. They sit on older concrete slabs without vapor barriers, and decades of marine-layer moisture have wicked up through the slab edges. Before we convert a garage in San Pedro, we check the slab, the roof framing, and the electrical service. A garage conversion ADU in San Pedro typically runs $30,000-$80,000, with the higher end reflecting foundation and moisture remediation on older homes near the port.
New Detached ADU
A new detached ADU in San Pedro costs more than one in Torrance, and here’s why: the fasteners. We specify hot-dip galvanized anchors, stainless window frames, and marine-grade hardware on every exterior surface. Zinc-plated hardware that holds up inland will rust through in under a decade in San Pedro’s salt air. A detached ADU in the 90732 hills above the port also usually needs a retaining wall that satisfies the Coastal Commission’s geotechnical requirements. We engineer it for saturated, shifting slopes, not for a flat inland lot.
Junior ADU & Interior Conversion
If you have an underused basement, a large laundry room, or a sunroom that was never properly conditioned, a Junior ADU can be the fastest path to rental income or an in-law suite. Interior conversions avoid most bluff-edge and Coastal Commission triggers because the footprint doesn’t change. But San Pedro’s older pier-and-beam foundations still need to be checked before we add a bathroom or kitchen load. We do that check before we quote, not after demo starts.
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 Pedro
When we build hardscape around a new ADU in San Pedro, we install what survives here. Techo-Bloc and Cambridge pavers with sealed joints hold up better than cheap box-store concrete pavers that spike and flake under marine-layer moisture. We use Quikrete products mixed to spec for coastal exposure when we pour footings and retaining walls. You can look up every material we specify. We don’t install mystery brands off a van.
Common Home Additions & ADU Problems We See in San Pedro Homes
- Rusted railing bolts and bracket screws. Galvanized hardware on decks and stairs near the port shear or crumble within five to seven years. We spec stainless or hot-dip galvanized on every exterior connection.
- Rotted pier-and-beam subfloor joints. San Pedro’s heavy marine layer keeps underfloor spaces damp for months. Add the constant micro-vibration from port trucks on Gaffey Street, and old subfloor joints that were fine for decades start sagging under a room addition’s load.
- Cracked bluff-edge ADU foundations. When Coastal Commission-required retaining walls are under-built for saturated clay slopes on the western bluffs, the foundation moves. We see this on lots in 90731 and 90732 that were developed before modern geotechnical standards existed.
- Exterior trim rot on additions. Salt-laden air from the open Pacific accelerates wood rot and rust on exposed fasteners. Materials that would last 30 years a few miles north in Torrance fail here in a decade. Our spec accounts for that from the first estimate.
Pricing for Home Additions & ADU in San Pedro, CA
The price gap between a coastal-spec addition and an inland-spec addition in San Pedro is real, and it’s worth understanding before you compare bids. Here’s what we currently see across San Pedro’s market:
| Project | San Pedro Price Range |
|---|---|
| Home Addition | $45,000-$130,000 |
| ADU Construction | $90,000-$220,000 |
| Garage Conversion | $30,000-$80,000 |
| Room Additions | $45,000-$130,000 |
What pushes a San Pedro project toward the top of those ranges? Bluff-edge lots in 90731-90732 that need Coastal Commission review, retaining walls, and deep foundation work. What pushes it down? A flat interior lot in 90734 with good soil and no view-corridor issues. The coastal-spec materials add roughly 8-15% to the exterior hardware and finish line items compared to an inland-spec bid. The cheaper spec costs more within a decade, when the fasteners rust and the trim rots. We’d rather quote the right spec once. Call (877) 610-1318 for a free estimate, and we’ll give you written numbers with the corrosion-resistant materials already included.
We Also Serve Cities Near San Pedro
Our crews work throughout the harbor area and the South Bay hills, so if you’re outside San Pedro proper we may already be working your street. We serve Lomita, Torrance, Rancho Palos Verdes, and Rolling Hills Estates, where the same salt air and port vibration issues apply but with different permit jurisdictions. Call us and we’ll let you know when we can get to your property.
Serving San Pedro, CA - Our Local Coverage Area
We’re based in the San Pedro 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 San Pedro
Yes, in many cases. ADUs on bluff-adjacent lots in 90731 and 90732 frequently get flagged for a Coastal Development Permit on top of standard LADBS approval. Whether yours requires one depends on your lot’s distance from the bluff edge, the degree of slope, and the footprint you’re proposing. We check that before we quote. Call (877) 610-1318 for a free estimate and we’ll tell you exactly what your lot triggers.
Stainless steel or marine-grade aluminum frames with powder-coat finishes survive best. Vinyl frames hold up reasonably well inland, but salt exposure near Point Fermin and the harbor accelerates seal failure. We specify Andersen and Marvin marine-grade lines on bluff-adjacent San Pedro additions and ADUs for exactly that reason. The upgrade costs more up front and lasts decades longer.
Expect to pay roughly 8-15% more for exterior materials when you spec hot-dip galvanized anchors, stainless fasteners, marine-grade window frames, and sealed paver joints. On a $150,000 detached ADU, that’s roughly $12,000-$22,000 in materials upgrades. The inland-spec version will likely need fastener replacement, trim repair, or railing rebuilds within ten years, often before the mortgage on the ADU is paid off. Call (877) 610-1318 and we’ll put the numbers in writing for your specific lot.
We reinforce the existing structure to handle it. San Pedro’s older Craftsman bungalows sit on pier-and-beam or early concrete foundations that were never engineered for the constant micro-vibration from port trucks on Gaffey and Harbor Boulevard. Before we add a second story, we evaluate the foundation, the subfloor structure, and the lateral bracing, then bring the whole assembly up to current seismic and vibration standards. Inspectors sign off on it. Permits get pulled.
You can, but we’d advise against it for exterior exposure on the western bluffs. Standard vinyl fence posts and rails degrade faster in salt-laden air, and the post hardware rusts. We recommend marine-grade aluminum or composite fencing with stainless hardware for yards in 90731 and 90732. The cost difference is modest, and the fence won’t start sagging or corroding in five years. We can quote both options for you.
Get a Written Estimate for Your San Pedro Home Addition or ADU
Planning a room addition, a second story, or an ADU in San Pedro is a big decision, and you deserve a contractor who will tell you what the salt air, the port, and the Coastal Commission are going to do to your budget before you sign. We give you scope in writing, allowances in writing, change orders in writing, and permits pulled on every eligible job. The 90-Day Done Right Promise is on the contract. Call Barrett & Sons Construction at (877) 610-1318 to schedule your free estimate. Tom Barrett and his sons will be the ones on your property, not a stranger from out of town.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving San Pedro since our first bluff-side addition years ago.