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 Marina del Rey
If you’re planning a home addition or ADU in Marina del Rey, the price you get from an out-of-town contractor is probably missing three or four line items that will show up later. A detatched ADU in Marina del Rey typically runs $90,000 to $220,000, and the spread comes down to foundation work, coastal permits, and site access. We’re Barrett & Sons Construction, and we’ve been building additions and accessory dwelling units long enough to know that in Marina del Rey, the paperwork matters as much as the framing. Call Tom and his sons at (877) 610-1318 when you want a written scope and a real number before you sign anything.
Why Barrett & Sons Construction Is Marina del Rey’s Preferred Home Additions & ADU Company
Tom Barrett puts his name, address, and license number on every proposal. Look him up. That’s the point. We’re not a franchise that dispatches strangers to your street in Marina del Rey; the sons run the crews, and Tom is on-site most days. Homeowners around the 90292 and 90295 zip codes have called us after a national company quoted one number on the phone and handed them a different bill at the door.
Marina del Rey is our kind of job site because it forces you to be thorough. This is unincorporated LA County, not City of LA, so permits run through LA County DPW, and every structural addition or ADU inside the Coastal Zone needs a California Coastal Commission Coastal Development Permit. We account for both from day one. Every price change comes as a written change order before a single nail moves. If the permit inspector flags something, we fix it, because the inspector works for you, not for me. That’s how we protect a $90,000 to $220,000 ADU investment in Marina del Rey.
Our Home Additions & ADU Services in Marina del Rey
New Detached ADU
Building a new detached ADU in Marina del Rey means starting with a geotechnical study if your parcel sits on the former marshland fill that underlies much of the harbor area. We design for deep pile foundations where the soil reports call for it, and we spec epoxy-coated rebar and stainless-steel connectors for anything within 1,000 feet of salt air. A standalone ADU here is not a shed with a bathroom; it’s engineered for liquefaction zones and coastal exposure.
ADU Design & Permitting
This is where out-of-area contractors go wrong in Marina del Rey. They pull the LA County DPW building permit and never file the California Coastal Commission Coastal Development Permit. Then the stop-work order arrives after foundation rough-in. We run both tracks in parallel, which is why our ADU permit timelines in Marina del Rey are measured in weeks, not months of surprise.
ADU Site Prep & Utilities
On larger Marina del Rey parcels, the placement of your ADU depends on existing septic leach fields and well setbacks. We survey for both before we breathe a word about floor plans. Grading and drainage matter here too. We direct sheet flow away from the slab so a Marina del Rey winter rain doesn’t find its way under your doors.
Garage Conversion ADU
Many homes in Marina del Rey were built between 1965 and 1985, and the garages on those older parcels often sit on slabs that were never designed for living space. Converting one means pouring a moisture break and tying into the existing foundation, and because of the local salt air, we upgrade the connectors and flashing as standard. A garage conversion ADU in Marina del Rey typically sits in the $30,000 to $80,000 range before you account for any coastal-condition foundation surprises.
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 Marina del Rey
We stock Simonton, Ply Gem, and PGT window and door lines for Marina del Rey jobs, and we keep local lead times predictable. Salt air is hard on aluminum and hardware, so we don’t put mystery-brand windows into a home a block from the marina. When a homeowner asks us to service an existing addition or ADU in Marina del Rey, we arrive with parts that match what we would install on our own build.
Common Home Additions & ADU Problems We See in Marina del Rey Homes
- Stop-work orders from missing Coastal Development Permits. A contractor pulls the LA County DPW permit, pours the foundation, and then the Coastal Commission shows up. We have seen this twice in Marina del Rey this year. Fixing it mid-build costs more than filing it right the first time.
- Foundation settlement on fill soils. Much of Marina del Rey was built on artificially filled tidal wetlands after the harbor opened in 1965. Standard spread footings work fine in Venice; they crack under load here. We require geotech on any structural addition.
- Ground lease sign-off problems. A lot of Marina del Rey parcels sit on LA County ground leases rather than fee-simple land. Before we scope anything structural, we verify the lease allows the improvement and obtain lessor sign-off. A non-refundable deposit on a lease that won’t sign off is money gone.
- Salt-corrosion on older additions. Waterfront Marina del Rey homes age faster than inland ones. Embedded rebar and metal connectors near the water corrode from chloride. When we open up an old addition for a remodel, we routinely find connectors we would not pass today.
Pricing for Home Additions & ADU in Marina del Rey, CA
A home addition in Marina del Rey generally lands between $45,000 and $130,000. A detached ADU runs $90,000 to $220,000. Garage conversions sit in the $30,000 to $80,000 band. The Marina del Rey premium over nearby cities comes from the dual permit path, the geotechnical studies the liquefaction-prone fill demands, and the coastal material upgrades. We scope every allowance and every change order in writing before work begins, so the number you approve is the number you pay. Call (877) 610-1318 and we’ll walk your property and put a fixed, written quote in your hand. Estimates are free, and so is the second opinion if you already have a written bid from another company.
| Service | Price Range in Marina del Rey |
|---|---|
| Home Addition | $45,000 - $130,000 |
| ADU Construction | $90,000 - $220,000 |
| Garage Conversion | $30,000 - $80,000 |
We Also Serve Cities Near Marina del Rey
If you’re just outside Marina del Rey, we work in Lawndale, Hermosa Beach, Redondo Beach, and Hawthorne too. The crews that serve Marina del Rey are the same ones that cover the surrounding coastal and South Bay neighborhoods, so you get a team that already knows the local Coastal Zone requirements. If you’re planning a home addition or ADU anywhere near the marina, call the team at Home Additions & ADU and we’ll let you know if your parcel falls inside one of the coastal or county overlay zones before you spend a dollar on design.
Serving Marina del Rey, CA - Our Local Coverage Area
We’re based in the Marina del Rey 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 Marina del Rey
An ADU in Marina del Rey requires a LA County DPW building permit and a California Coastal Commission Coastal Development Permit because the entire community sits inside the California Coastal Zone. Plan for 4 to 12 weeks of additional review beyond what a standard county permit takes. We run both applications in parallel from the first week, which keeps the combined timeline as short as the Coastal Commission calendar allows. Call (877) 610-1318 for a realistic permit schedule on your specific parcel.
Yes, if your parcel sits on a LA County ground lease rather than fee-simple land, which applies to a meaningful portion of Marina del Rey. The lessor must sign off on any structural improvement before a permit will hold. We check the lease terms and secure that sign-off before we pull the Coastal Development Permit or the DPW building permit. If a contractor skips that step, you can lose your deposit and your schedule. Call us before you sign anything and we’ll verify the lease for you.
Your septic leach field and any on-site well impose required setback distances that control where an ADU can sit, and on larger Marina del Rey lots those setbacks often shrink the buildable area more than zoning does. We measure the field and well first, then design the ADU footprint around them. Grading also matters; we slope the pad so sheet flow runs away from the slab and toward the approved drainage path. Call (877) 610-1318 and we’ll walk your lot and mark the buildable envelope before you pay for plans.
Because Marina del Rey was built almost entirely on artificially filled former tidal wetlands after the harbor opened in 1965, and the state maps virtually the whole community inside liquefaction hazard zones. Venice and Culver City sit on more stable natural soils in many areas. Here, we routinely bring in a geotech, then design deep pile foundations that spec epoxy-coated rebar if the job is within 1,000 feet of the salt air. That’s a real line item, and it is why a generic out-of-town quote for a Marina del Rey ADU is usually low. Call (877) 610-1318 for a written scope that includes the geotech and foundation line items from day one.
Yes, especially for any structure east of the main channel or within about 1,000 feet of the water. The marine layer and direct Pacific exposure accelerate chloride-driven corrosion of embedded rebar, metal connectors, and aluminum framing. We spec epoxy-coated rebar, stainless-steel connectors, and upgraded flashing on our Marina del Rey builds. And we don’t leave those choices to chance; they are written into the scope before we start. Call (877) 610-1318 to talk about what your parcel needs.
Get a Written, Fixed Estimate for Your Marina del Rey Home Addition or ADU
Tom Barrett owns this company, answers his own phone, and stands behind every line item. Our 90-Day Done Right Promise is written on every contract: if it’s not done right, one call brings Tom back. Permits pulled, inspections signed, change orders in writing. Call (877) 610-1318 to schedule your free estimate, and ask for the Senior & Veteran discount if it applies. If you already have a written bid, bring it; the second opinion is free too.
Written by Tom Barrett, Owner at Barrett & Sons Construction, serving Marina del Rey and the surrounding South Bay communities.