ADU (accessory dwelling unit) Cost in Washington: Home Prices and Standard Setup
Washington ADU home prices start at $85,500 for Model K. Compare standard setup, exclusions, permitting, delivery and property-specific work.
Home starting prices and your property
Home starting prices outside Portland begin at $85,500 for Model K. Availability and property fit need review.
Starting prices cover the home itself. Your property proposal covers the work needed around it.
Site work, foundation, utility connections, delivery, and installation are quoted for your property. Your written proposal defines the scope, taxes, appliances, and any additional work.
| Part of your project | How it is priced |
|---|---|
| Starting price for the home | $85,500 (Model K, home only) |
| Appliances and selected upgrades | Priced separately in your proposal |
| Permitting and local fees | Confirmed for your jurisdiction and project |
| Delivery and installation | Quoted for your address, access, and placement needs |
| Foundation, site work, and utilities | Quoted after reviewing the property |
Your proposal shows the home price and site work separately. Trench length, septic or sewer work, electrical upgrades, access, foundation, ramps, and delivery distance are reviewed for your property. Taxes, appliances, and work outside the agreed scope are priced separately.
These are Wolf’s published planning ranges for a Washington ADU. The table matches the cost and budget information on our FAQ page. A property review is still required for an installed price.
What the published numbers cover
Model K starts at $85,500 for the home itself. This 432-square-foot one-bedroom plan is the lowest-priced current model available in Washington. Model B is limited to Portland city limits in Oregon. You can see the starting price for every floor plan on the models page. These prices do not include appliances, delivery, installation, permitting, or site work. You can purchase our appliance package or provide your own.
Your complete project is quoted for your property. The written proposal defines what is covered, including required site work, utility connections, permits, delivery, installation, and any separate taxes, appliances or selections.
Permitting and agency fees are confirmed for your project. Obtain an itemized estimate of jurisdiction and utility charges. Washington’s ADU impact-fee cap applies in covered urban areas under RCW 36.70A.680 and .681. It does not cap every utility charge or establish the same rules for rural lots outside the UGA.
Installation is quoted after a property review. The scope can include excavation, foundation, utility trenching, delivery, placement, connections, and final inspection. Your proposal confirms the work for your address, including any longer trench, well or septic work, electrical upgrades, or delivery requirements.
Why two Washington lots with the same model are not the same budget
The factory is at 607 SE Eaton Blvd in Battle Ground. That shortens delivery to Battle Ground and Vancouver, but site work still varies from lot to lot.
- City vs county. A Battle Ground mailing address can sit in city limits or unincorporated Clark County. Vancouver mailing addresses do the same along Hazel Dell, Felida, and Salmon Creek. Pull Clark County GIS before you budget so you know whether the city or the county reviews the permit.
- Urban vs rural. Washington’s urban ADU protections apply to covered jurisdictions and eligible lots, with statutory exceptions. Rural ADUs follow a different process. In Clark County, well and septic questions can require Public Health’s WAVE review before a project proceeds; see the county guide for the applicable path.
- Utilities. Confirm the actual water and wastewater providers, connection route, capacity, and electrical load. An existing well or septic system does not establish that another dwelling can use it. Price any necessary upgrades in the proposal.
- Access. Delivery depends on the selected home’s dimensions, turning space, overhead lines, street restrictions, and the route to the foundation. A nearby address alone does not establish the delivery method, time, or price.
We review those site conditions before recommending a model or presenting an installed cost.
How to plan your budget
- Start with the table for the home price and the costs to confirm. The model baseline table adds home and standard setup prices; it excludes fees, appliances, taxes and additional property work.
- Read the Washington ADU laws guide for the statute, then the county guide that matches your parcel.
- If the lot is in Battle Ground or Vancouver, check our local notes on jurisdiction and delivery. If it is unincorporated Clark, read our Clark County notes and the Clark County ADU rules guide.
- Send the address. The evaluation is free and identifies the further site, utility, or agency checks needed for a written project proposal.
Financing options include home equity, renovation, and construction loans, subject to lender approval and payment timing. See financing.
Wolf homes are modular, not HUD (the federal standard for manufactured homes) manufactured housing. Washington L&I inspects the structure in the factory, while local inspectors review the foundation, placement, and utilities. That’s why we can list a starting price for the home but need to see the property before pricing the complete project.
Compare factory modular to on-site stick-built on prefab ADU vs stick-built. If you are weighing a local on-site builder, start with Wolf vs RG ProBuilders.
Common questions
How much does a Wolf ADU cost in Washington?
What’s the difference between an ADU, a tiny home, and a modular home?
Why don’t you publish one all-in Washington price?
Where should I start if my lot is in Battle Ground or Vancouver?
Sources
Requirements change, so check the current forms and rules with your jurisdiction before you file. This is general information, not legal advice.