A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in Kensington, CA
An ADU, or accessory dwelling unit, is a second, smaller home built on the same lot as your main house – and in Kensington, that usually means building on a slope, under Contra Costa County hillside rules, and with fire-safety requirements baked into the design from day one. We’re Lodgewick ADU Builders, part of the Kingswell family of home-service companies, and we handle accessory dwelling units, garage conversions, and home additions across Kensington. If you’re weighing an ADU against a garage conversion or a room addition, this page gives you the lay of the land – and you can call (707) 760-0502 when you want a written price for your specific lot.
Why Kensington Homes Are Different
Kensington isn’t like the flatlands of Berkeley or El Cerrito. It’s an unincorporated hillside community in Contra Costa County, which means there’s no city planning desk reviewing your ADU plans – the county handles everything, from setbacks to grading to fire-hardening requirements. Many of the homes here were built in the 1940s through the 1960s, and they sit on sloped lots with original foundations that were never designed to carry a second structure’s drainage or retaining-wall loads. That’s the first thing we look at on any Kensington ADU project: what’s holding the lot up, and where the water goes when it rains.
The wildfire risk zone shapes materials choices, too. Kensington sits in a high-severity fire hazard area, so exterior cladding, vents, and roof assemblies have to meet the county’s wildfire-resistant standards. We specify fiber-cement siding from James Hardie and fire-rated venting as standard on hillside lots, not as upgrades. And then there’s the logistics: Kensington’s winding, narrow roads – think along Arlington Avenue and the lanes off it – can make getting a concrete truck or a crane to the site the single hardest part of the job. Tight turnarounds, low-hanging trees, and steep driveways mean every one of our Kensington projects starts with a written traffic and access plan before we ever pour a footing.
Our Main Kensington Services
Most Kensington homeowners come to us weighing three options: a detached ADU in the yard, a garage conversion that turns existing square footage into a rental or in-law unit, or a home addition that extends the main house. Each has its own Kensington page.
Home Addition Contractor in Kensington
A home addition in Kensington usually means building into the hill or cantilevering over a downslope, which brings foundation piers, retaining walls, and drainage into the equation early. We frequently see original mid-century homes where the rear yard drops away steeply, so the addition has to be engineered as much as built. If you’re thinking about adding a primary suite or a family room, the full scope of what that takes on a Kensington hillside lot is on our Home Addition Contractor in Kensington page.
Garage Conversion Contractor in Kensington
Garage conversions are a smart play in Kensington because the footprint already exists – what changes is the use. The usual challenges here are structural: original garage slabs poured thin, walls never insulated, and grade that slopes toward the house. Converting that space into a legal dwelling means county-required upgrades to foundation anchorage, electrical service, and fire separation. We cover the Kensington-specific details, including what Contra Costa County requires, on our Garage Conversion Contractor in Kensington page.
ADU Builders in Kensington
Detached ADUs in Kensington have to work with the land, not against it. That means hillside setbacks, foundation types matched to the soil, and a roofline that doesn’t fight the existing house. Prefab ADUs from Abodu and Cover can shorten on-site time dramatically on Kensington’s tight lots, but we also do stick-built units where the site calls for it. The full breakdown – including what prefab works well on a Kensington lot and what doesn’t – is on our ADU Builders in Kensington page.
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 Kensington
We work with ADU brands that hold up on Kensington’s hillsides and in its fire zone: Abodu and Cover for prefab units, Tuff Shed for backyard studios and workshops, and James Hardie for fiber-cement siding that meets wildfire-resistant cladding requirements. See our brands for the full lineup and what we recommend for sloped lots.
Pricing for ADU Company in Kensington, CA
| Service | Typical range in Kensington |
|---|---|
| Detached ADU (prefab, 400 – 600 sq ft) | $180,000 – $280,000 |
| Detached ADU (stick-built, 400 – 600 sq ft) | $250,000 – $380,000 |
| Garage conversion to ADU | $120,000 – $220,000 |
| Garage conversion to living space (non-rental) | $80,000 – $150,000 |
| Second-story home addition | $300,000 – $500,000+ |
| Ground-level home addition | $200,000 – $350,000 |
| Hillside foundation and retaining wall work | $25,000 – $80,000 |
| Drainage and erosion control | $8,000 – $25,000 |
| Fire-hardened exterior upgrade (siding, vents, roof) | $30,000 – $70,000 |
| Site access and logistics planning (crane, narrow-road staging) | $5,000 – $15,000 |
What pushes a Kensington ADU price higher than the same job on flat ground: hillside foundation engineering, retaining walls, drainage systems, and the crane or pump-truck logistics that narrow roads force on us. Fire-resistant materials also add cost, though they’re non-negotiable in this zone. Whatever the scope, you get a written price before any work starts – that’s the Kingswell Guarantee, and we don’t change the number at the door.
Neighborhoods We Serve in Kensington
We work throughout Kensington, from the flats near Colusa Circle up to the ridge lines and everything between. Our typical response window for a Kensington estimate visit is 2 to 4 business days, depending on how many site walks are already on the books that week.
- Arlington Avenue corridor
- Colusa Circle area
- Upper Kensington ridgeline
- Berkeley Country Club vicinity
- Lower Kensington flats
Service Area – Cities Near Kensington
Kensington sits just north of the Alameda-Contra Costa county line, and we regularly take on projects across the broader East Bay. We handle ADUs, garage conversions, and additions in San Francisco, CA, Oakland, CA, Hayward, CA, and Richmond, CA. Each of those pages covers the local conditions for that city the same way this one does for Kensington.
Serving Kensington, CA - Our Local Coverage Area
We’re based in the Kensington 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 Kensington
Yes. Kensington is unincorporated, so Contra Costa County issues all building and grading permits, and hillside lots usually require a soils report and drainage plan as part of the submittal. We handle permits as part of every project, and the written price includes permit fees.
A prefab ADU typically takes 6 to 9 months from permit submittal to move-in, while a stick-built unit on a steep lot runs 10 to 14 months. County review times, grading-season weather, and crane logistics on narrow roads are the usual variables. Call (707) 760-0502 to get a timeline for your specific lot.
No. The price we put in writing before work begins is the price you pay unless you change the scope. The Kingswell Guarantee is specific about this, and it’s one of the reasons homeowners who’ve been burned by contractors call us. We also put a written workmanship guarantee on every Kensington project, with a free return visit if something fails within 365 days – that’s the 365-Day Done Right Promise.
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 Kensington Customers Say
"The ADU came out beautiful and the permitting, which terrified me, was handled start to finish. They kept me updated every week so I was never wondering what was happening."
- Shauna Mills"Turned our detached garage into a little guest house. Clean crew, respectful of the neighbors, and no mystery charges at the end. Love how it turned out."
- Carmela Fontes"I was nervous about adding on but they walked me through every step and every cost before we started. No surprise change orders halfway through like I'd heard horror stories about."
- Eleanor Pratt
