A free site visit, a check of what your lot allows and a written, line-item price.
Get your free estimateADU Company in San Dimas, CA
Adding an ADU, home addition, or room addition in San Dimas means working with a city that has its own rhythm: foothill lots, older ranch homes on roomy parcels, and a planning department that asks for real site plans before anything gets framed. We’re Sutton ADU Builders, the ADU-specialist member of the Threshold Group family, and every San Dimas project starts the same way: a written price before work begins, a background-checked and photo-badged crew, and a 365-Day Done Right Promise covering the work for a full year. If you’re pricing out a detached ADU or a room addition, call (472) 248-8213 and we’ll walk you through what your lot can actually support.
Why San Dimas Homes Are Different
San Dimas sits against the San Gabriel foothills, and that geography shows up in the housing stock. Many homes here were built between the 1950s and 1980s, so we regularly work with slab foundations, older electrical panels, and lots that slope enough to matter for drainage. A setback, the required gap between your new structure and the property line, can get tighter on hillside parcels, and the city takes seriously how runoff from a new ADU roof or addition flows toward neighboring lots. That means grading, retaining walls, and drain lines often become part of the real scope, not an afterthought.
We also see a lot of the original ranch and split-level layouts that were common when much of San Dimas was developed. Those homes give you decent lot coverage to work with, but the utilities are almost never where a modern ADU needs them. Panel upgrades, sewer lateral reconnects, and sometimes a new water service line are normal line items here. None of this is a surprise if the estimate accounts for it up front, which is exactly how we write our numbers.
Our Main San Dimas Services
Most San Dimas homeowners calling us are weighing two or three options for adding square footage, and each one has its own page with pricing and local detail. Here’s where to start.
Home Addition Contractor in San Dimas
A home addition in San Dimas usually means extending a single-story footprint outward, and on these lots that often runs into slope and setback questions early. We plan the foundation, roofline tie-in, and existing wall integration as one scope, and handle the permit drawings the city wants to see. If you’re comparing an addition against a detached unit, read the numbers and process on the Home Addition Contractor in San Dimas page.
ADU Builders in San Dimas
Detached ADUs in San Dimas are governed by California state ADU law plus local zoning overlays, and the practical question is usually where on the lot the unit can go while keeping driveway access and a usable yard. We build site-built and prefab ADUs, and we’re honest about which product line fits a given parcel before you spend money on plans. The full cost breakdown and common San Dimas lot issues are on the ADU Builders in San Dimas page.
Room Addition Contractor in San Dimas
A room addition here frequently means adding a bedroom, home office, or family room off the back of a 1960s-to-1980s home, which puts the new foundation right up against older framing and slab work. We quote the whole job: demo, foundation, framing, roofing, drywall, finish, and the electrical and HVAC extensions. For a detailed scope and what it costs, see the Room Addition Contractor in San Dimas 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 San Dimas
We have authorized experience with Abodu, Cover, Dvele, and Mighty Buildings prefab ADU lines, and we service them across San Dimas. Stock availability for common components moves through our local suppliers, so turnaround depends on the product line and your site conditions. Full detail on what we service is on our our brands page.
Pricing for ADU Company in San Dimas, CA
Here are the honest ranges we quote for work in San Dimas. These are written-price ranges, not vague estimates, and they reflect the foothill-lot conditions we actually build on here.
| Service | Typical range in San Dimas |
|---|---|
| Detached ADU (350 – 500 sq ft) | $180,000 – $320,000 |
| Detached ADU (500 – 800 sq ft) | $240,000 – $410,000 |
| Detached ADU (800 – 1,200 sq ft) | $320,000 – $545,000 |
| Garage conversion ADU | $110,000 – $215,000 |
| Prefab ADU (product plus site work) | $215,000 – $420,000 |
| Home addition (300 – 500 sq ft) | $165,000 – $290,000 |
| Home addition (500 – 800 sq ft) | $240,000 – $410,000 |
| Room addition (250 – 450 sq ft) | $95,000 – $185,000 |
| Room addition (450 – 800 sq ft) | $150,000 – $310,000 |
Two things push San Dimas pricing above a flat valley lot: slope work and drainage. A hillside parcel often needs a retaining wall or a longer foundation stem wall, and stormwater management is taken seriously here. Whatever your lot requires, you get a written price before any work starts, and that number is what you pay unless you change the scope.
Neighborhoods We Serve in San Dimas
We work across the residential streets of San Dimas, from the flats north of Arrow Highway up into the foothill streets below the San Dimas Canyon area. Every neighborhood has its own mix of lot sizes and slope conditions, and that shapes both the build and the permit conversation.
- Foothill neighborhoods below San Dimas Canyon
- Areas near downtown San Dimas along Bonita Avenue
- Residential streets around Via Verde and San Dimas Avenue
- Neighborhoods east of Lone Hill Avenue
- Streets off Arrow Highway and Gladstone
Response time for an estimate visit in San Dimas is typically within a few business days, and we schedule around your availability, not the other way around.
Service Area – Cities Near San Dimas
If you’re just outside San Dimas, we also serve nearby communities with the same written-price and Threshold Verified standards. That includes La Verne, CA, Glendora, CA, Covina, CA, and Azusa, CA. Each city has its own local conditions, and our crew standards travel with us.
Serving San Dimas, CA - Our Local Coverage Area
We’re based in the San Dimas 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 San Dimas
We schedule estimate visits within a few business days for most San Dimas addresses. Once you approve the written price, the project timeline depends on city permit review and your product choices, and we lay that out clearly before you commit. Call (472) 248-8213 to get the conversation started.
We handle city permits and all required drawings, and we’ll tell you early whether an HOA design review applies to your ADU or addition. Some San Dimas neighborhoods have active HOAs that review exterior elevations. Your written price reflects the permit scope we can see at the time of quote, and we flag any unknowns before they become change orders.
Yes. Before anyone arrives on your property, we send you their name and photo. Every technician is background-checked, identity-verified, uniformed, and photo-badged, and they’ll show that badge at the door. That’s the Threshold Standard, and it applies to every visit on your San Dimas project.
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 San Dimas Customers Say
"They handled the drawings and the permit paperwork for us. All I had to do was pick the finishes."
- Rosa M."Every crew member was vetted and carried a badge, which matters when they are around your family for months. Tidy site every day."
- Daniel F."Itemized estimate with allowances laid out. Final cost was within a hair of the quote."
- Naomi R.
