Beyond kitchens, baths, and repairs, RestorationRepublic takes on a small number of additional dwelling unit projects each year — garage conversions, detached backyard cottages, and foundation-built tiny homes across Clark County. These are small house projects, not remodels, and they succeed or fail in the planning phase.
ADU vs. tiny home: what's actually allowed here
The terms get used interchangeably, but Clark County treats them very differently:
- ADU (Accessory Dwelling Unit). A permanent, code-built secondary dwelling on the same lot as your home — attached, detached, or converted from existing space like a garage or basement. Fully legal in most residential zones with permits.
- Tiny home on a foundation. A small detached dwelling built to the same building code as any house. On most lots this is permitted as an ADU — same rules, same permits, just smaller.
- Tiny home on wheels (THOW). Legally an RV in Washington. It cannot be used as a permanent residence on a standard residential lot in Clark County, no matter how well it's built.
Before you buy a tiny home: if it's on wheels, plan on RV parks and designated communities — not your backyard. If you want a small dwelling on your own lot, build it on a foundation as a permitted ADU.
The three realistic paths in Clark County
| Path | Typical cost | Timeline |
|---|---|---|
| Garage conversion to ADU | $80k–$150k | 4–6 months |
| Basement or attached conversion | $70k–$140k | 3–6 months |
| Detached ADU / tiny home on foundation | $150k–$300k+ | 8–12 months |
These are planning ranges, not quotes — site conditions, utility distance, and finish level move them significantly. A firm number only exists after a site walk, feasibility check, and written scope.
Feasibility: the step everyone skips
Four questions decide whether your project is viable before a dollar is spent on design:
- Zoning and setbacks. Clark County and the cities inside it (Vancouver, Camas, Battle Ground, Washougal, Ridgefield) each have their own ADU size limits, setback rules, and parking requirements. Get it in writing.
- Electrical capacity. Many older Clark County homes have 100-amp panels that can't carry a second dwelling. A panel or service upgrade can add thousands to the budget.
- Sewer or septic. City sewer usually means a tie-in and possibly a new side sewer; septic systems must be sized for the added load or expanded — a common five-figure surprise on rural lots in Brush Prairie, La Center, or Woodland.
- Water service. Meter size and pressure must support two dwellings; some conversions share the existing service, others need a new meter.
Thinking about an ADU or tiny home on your lot?
Send us your address and a sentence about what you're picturing. We'll tell you what's realistic for your lot, utilities, and budget — before you spend money on plans.
What a conversion or build actually involves
Garage conversion
The envelope exists, so the work is structural verification, insulation and moisture control, new windows and egress, a raised insulated floor, full electrical, plumbing for a kitchen and bath, HVAC (usually a ductless mini-split), and fire separation from the main house. Ceiling height and the existing slab condition are the two make-or-break items.
Detached ADU or tiny home on foundation
This is ground-up construction at small scale: foundation, framing, roofing, siding, full mechanical systems, and finishes — every trade a full house needs, sequenced the same way. The economy comes from size, not from skipping steps. Compact design choices (wet-wall plumbing layouts, combined laundry, vaulted ceilings) decide how livable a 400–800 sq ft unit feels.
Permits and inspections in Clark County
Every ADU project runs through building, electrical, plumbing, and mechanical permits, with inspections at footing, framing, rough-in, insulation, and final. Rural parcels add septic review through Clark County Public Health. Whoever builds your unit should pull the permits in their name and schedule every inspection — if a contractor suggests skipping permits "to save time," walk away.
Why one contract matters on a small project
An ADU touches at least six trades: concrete, framing, electrical, plumbing, HVAC, and finishes. On a project this size, coordinating six separate bids and schedules usually costs more in delays than it saves. RestorationRepublic manages the entire build under one fixed scope — one timeline, one point of contact, and one party accountable for the finished unit passing final inspection.
Frequently asked questions
Is a tiny home on wheels legal as a residence in Clark County?
Generally no. A tiny home on wheels is classified as a recreational vehicle and cannot be used as a permanent dwelling on most residential lots in Clark County. A tiny home built on a permanent foundation that meets building code can qualify as an ADU. Always confirm with Clark County Community Development before you buy or build.
What's the difference between converting a garage and building a detached ADU?
A garage conversion reuses an existing permitted structure, so it is usually faster and cheaper — often $80,000–$150,000. A detached ADU is new construction with a new foundation, utility runs, and full code compliance, typically $150,000–$300,000+. The right choice depends on your lot, budget, and whether the garage is structurally worth keeping.
Do I need a permit for an ADU or tiny home in Clark County?
Yes. Any permanent dwelling — ADU, garage conversion, or foundation-built tiny home — requires a building permit, plus separate electrical, plumbing, and mechanical permits. Unpermitted units can block a future sale, void insurance claims, and trigger county enforcement. We pull all permits as part of the scope.
Can my existing utilities support an ADU?
Sometimes. The three usual constraints are electrical panel capacity, sewer or septic capacity, and water service size. These must be verified in writing before design — an undersized panel or septic system can change the entire project budget.
How long does an ADU project take in Clark County?
A garage conversion typically runs 4–6 months including permits. A detached new-build ADU usually runs 8–12 months from feasibility to final inspection. Permitting and utility reviews are the most common source of delay.
Keep reading
RestorationRepublic manages ADU feasibility, permits, and construction under one written scope across Vancouver, Camas, Battle Ground, Washougal, Ridgefield, and greater Clark County.
Talk to a real project manager
RestorationRepublic handles kitchens, baths, repairs, and water damage across SW Washington — one licensed contractor, one written scope, one accountable point of contact.
Request an ADU Feasibility Review