A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Manhattan Beach, CA
Adding an ADU in Manhattan Beach means working with tight lots, coastal setbacks, and a city that reviews every plan carefully before a single footing gets poured. We’re Benson ADU Builders, and we handle the whole thing: design, permits, prefab or site-built construction, and the final walkthrough. Most Manhattan Beach projects land between $280,000 and $450,000 depending on size, access, and finish level. Call (903) 568-7222 and we’ll walk you through what’s realistic for your specific property.
Why Manhattan Beach Homes Are Different
Manhattan Beach lots tend to be narrow and deep, often 30 by 90 feet, which pushes ADU design toward two-story builds or detached units tucked along the rear alley. Many homes here were built between the 1940s and 1970s, so we regularly deal with older foundations, outdated electrical panels, and sewer lines that need upsizing before an ADU can tie in. The coastal marine layer also matters: salt air corrodes exposed metal hardware faster than inland, so we spec stainless connectors and coastal-rated fasteners on every exterior detail.
Homes in the Sand Section and Hill Section sit on steep grades or compacted sand, which changes foundation engineering and sometimes adds helical pier costs. The Tree Section has more mature landscaping to work around, and protected trees can shift where your ADU sits within the setback envelope. Manhattan Beach also has its own coastal development review. If your property falls inside the coastal zone, you may need a coastal development permit on top of the standard building permit, which can add several weeks. We handle that paperwork for you, and we put the full permit path in writing before anything starts.
Our Main Manhattan Beach Services
Most Manhattan Beach homeowners call us for one of three things. Each service has its own dedicated Manhattan Beach page with pricing, timelines, and deeper detail:
ADU Builders in Manhattan Beach
A detached ADU in Manhattan Beach typically runs 400 to 1,200 square feet, and the site matters as much as the floor plan. Alley-loaded lots give us direct backyard access for equipment and panels; street-loaded lots sometimes mean a crane day or careful hand-carry through a side gate. We build with prefab systems from Abodu and Cover when the lot access supports it, and we go site-built when a custom layout or coastal-zone design review calls for it. Either way, you get a written price before work starts and a 365-Day Done Right Promise on the finished unit. ADU Builders in Manhattan Beach
Home Addition Contractor in Manhattan Beach
Home additions here usually mean expanding into the side yard or building up over a garage, because most Manhattan Beach lots have nowhere left to go out. We see a lot of second-story additions that add two bedrooms and a bath while keeping the existing footprint untouched below. The catch is structural: 1970s framing often needs shear-wall upgrades and foundation reinforcement to carry the new load, and the city’s plan checker will ask for those calcs. We get the engineering done early so there are no mid-project surprises. Home Addition Contractor in Manhattan Beach
Room Addition Contractor in Manhattan Beach
The most common room addition request in Manhattan Beach is a ground-floor family room off the back of the house, or a home office conversion where a covered patio sits now. These are smaller jobs, often 200 to 400 square feet, but they still trigger the full permit review because the city treats any conditioned-space expansion the same. We pull permits on every room addition, no exceptions, and we write the permit fees into your upfront price so you see the full cost before we start. Room Addition Contractor in Manhattan Beach
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.
Brands We Service in Manhattan Beach
We build with prefab systems from our brands including Abodu, Cover, and Dvele, and we finish exteriors with James Hardie cladding for salt-air durability. Panels are ordered to spec for your Manhattan Beach lot and arrive pre-cut, which cuts on-site framing time by weeks on most ADU jobs.
Pricing for ADU Company in Manhattan Beach, CA
| Service | Typical range in Manhattan Beach |
|---|---|
| Prefab ADU (turnkey, permit-ready plans) | $280,000 – $350,000 |
| Site-built detached ADU | $300,000 – $450,000 |
| Garage conversion ADU | $120,000 – $230,000 |
| Second-story addition (two bedrooms, one bath) | $260,000 – $420,000 |
| Ground-floor room addition (200 – 400 sq ft) | $140,000 – $260,000 |
| Kitchen expansion (150 – 300 sq ft) | $90,000 – $180,000 |
| Bathroom addition | $40,000 – $85,000 |
| Structural upgrades for second-story loads | $15,000 – $55,000 |
| Sewer line upsizing or connection revision | $6,000 – $18,000 |
| Coastal development permit support | $3,000 – $9,000 |
Prices in Manhattan Beach push upward when a lot falls inside the coastal zone, when soils require deeper footings or piers, or when the existing main house has structural upgrades that must happen before an ADU can share a wall or roofline. Every project gets a written price before work starts, and that number does not change at the door.
Neighborhoods We Serve in Manhattan Beach
We work across Manhattan Beach, and each neighborhood brings its own site conditions to the plan. Most projects we schedule within two to three weeks for the initial walkthrough and written estimate.
- Sand Section
- Hill Section
- Tree Section
- East Manhattan Beach
- El Porto
Service Area – Cities Near Manhattan Beach
If you’re just outside Manhattan Beach, we also cover nearby beach and South Bay communities. See our pages for Hermosa Beach, CA, El Segundo, CA, Lawndale, CA, and Hawthorne, CA. Dispatch and scheduling are coordinated from our Los Angeles office, and crews serve Manhattan Beach locally.
Serving Manhattan Beach, CA - Our Local Coverage Area
We’re based in the Manhattan Beach 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 About ADU Company in Manhattan Beach
Most Manhattan Beach walkthroughs happen within two to three weeks of your call. The full permit and build timeline depends on your lot’s zone and whether you’re inside the coastal development review area, and we lay that path out for you in writing at the first meeting. Call (903) 568-7222 to schedule the estimate.
Properties inside the coastal zone often need a coastal development permit in addition to the standard building permit. Not every Manhattan Beach lot falls inside that boundary, but we check your address against the city’s map before we quote anything. Either way, we handle the full permit package for you.
Hill Section and Sand Section homes sometimes need deeper footings, helical piers, or retaining work before construction starts. We bring in a soils engineer during the design phase, so foundation costs are baked into your written price from the beginning, not added later as a change order. Call (903) 568-7222 for a free estimate.
What happens when you call
- 1A real person answersNo phone trees - talk to a local adu pro.
- 2You get an upfront price rangeHonest numbers before anyone is dispatched. No surprises.
- 3We come out and measureLicensed & insured, at a time that suits you - the visit and the quote are both free.
- 4You get the price in writingLine-itemed, yours to keep, and nothing starts until you say go.
What Manhattan Beach Customers Say
"Booked a consult online and met the project manager two days later. Weekly progress updates arrived by text with photos. ADU finished on schedule."
- Hannah W."Clean, quiet crew. They respected the neighbors, kept noise to working hours, and swept the driveway every evening."
- Hope C."Communication was the best part. I always knew what was happening that week without having to ask."
- Dolly N.
