Building permits, zoning and land rules in Adams County, Washington

Yes. The Adams County Building Department reviews permit applications for building projects in unincorporated Adams County and in Lind, Hatton and Washtucna; town projects need town approval before county submittal, while Othello and Ritzville are outside this review scope¹. Permits generally cover new homes, mobile-home moves, repairs, additions, plumbing, reroofing, replacement windows, solid-fuel stoves and gas inserts⁸.

County submittals must be complete for acceptance and include the application, site plan, complete construction drawings, design criteria and fee information¹. The county publishes a master fee schedule, but the amount depends on the application, so confirm the total with Building & Planning². County-reviewed work follows the 2021 Washington State Codes, including the state Energy Code, in effect since March 15, 2024, and receives inspections through the phases of construction^1,9. The county's inspection page notes that inspections called in after 4 p.m. will not be scheduled for the next day⁹. Confirm any exemption before starting work.

Adams County Building & Planning is the first stop for a project in the county building jurisdiction. The Building Division enforces the Washington State Building Code, and its Othello office handles questions by phone at the contact listed above⁹. Building-permit applications can go through CloudPermit, and every submittal must be complete for acceptance¹.

The Building Division reviews plans and performs inspections through construction, while Planning handles zoning, subdivisions and parcel-specific land-use questions^2,9. A Washington owner may qualify for a contractor-registration exemption when working on their own property, unless the work is for selling, demolishing or leasing the property; the exemption covers contractor registration only, not building, electrical, plumbing or septic permits^6,10. For permit records, contact Building & Planning with the parcel number and property address.

Yes. Adams County administers zoning and land-use controls in unincorporated areas, while incorporated municipalities may administer separate rules². The mapped district matters: rural-district minimum lot areas range from 1 acre in R-1 to 20 acres per dwelling in R-20¹¹. Rural residential setbacks are also district-specific; front setbacks are 25 feet in R-1 through R-2.5 and 50 feet in R-5 and R-20, with other setbacks and special rules also applying¹¹.

Ask Planning to confirm the current table and parcel zoning before designing because the cited dimensional document is marked as a draft¹¹. Accessory dwelling units may be allowed on residential-zoned lots with an existing or proposed single-family dwelling, subject to county conditions⁵. An ADU must be at least 400 square feet, with one ADU per legal lot, though tiny-home ADUs are excepted from that minimum; the usual maximum is 1,000 square feet, rising to the lesser of 1,500 square feet or 65% of the main home's living area on lots of 2.5 acres or more⁵. An attached ADU shares the main home's septic and water system unless the Adams County health department issues a separate septic permit⁵. We could not confirm a universal minimum size for a main dwelling, lot-coverage limit or height limit, or a general agricultural-building exemption, so take those questions to Building & Planning. The county publishes its zoning code and map, last updated August 2025, covering rural, agricultural, residential and rural-settlement districts¹². Dividing land is regulated too: the Planning Division processes short plats, and a short-plat application needs water-availability and septic or sewer documentation¹³.

Adams County Health Department's Environmental Health program reviews septic plans and administers liquid-waste permitting, compliance and inspections³. A residence needs a septic permit or Existing System Evaluation unless city or community sewer is available, in which case the sewer provider's availability letter is required⁸. The county's site-registration form can accompany a sewage-permit application and compliant system design¹⁴.

For permitted on-site sewage work, the local health officer inspects during site evaluation, construction or final construction and confirms the finished system against the approved design⁴. About 41% of mapped county soils lack severe limits for a conventional drain field, so a parcel-level evaluation matters before purchase¹⁵. Adams County's short-term-rental rule permits compliant septic rather than requiring a public-sewer connection, but it ties occupancy to septic design capacity; the county's broader rules for alternative off-grid sanitation could not be confirmed⁵.

Adams County allows tiny-home construction and habitation under conditions in residential districts where single-family housing is allowed⁵. A tiny home used as a single-family dwelling must meet that zone's single-family requirements, while a tiny home used as an accessory dwelling follows the county's ADU rules with an exception to the ADU minimum-size provision⁵. Take the parcel number and proposed unit to Building & Planning before ordering it.

In an Adams County RV park, an RV may occupy the park for no more than 180 consecutive days or 180 calendar days in a year⁵. A campground or RV park may use one manufactured home as a caretaker residence, but no other manufactured home may be occupied, stored or parked there⁵. Neither rule answers whether an owner may live long-term in an RV on an ordinary private parcel; ask Planning before relying on an RV for housing or temporary camping.

If you plan to place a manufactured home, note the county's age rule: as of August 19, 2025, new manufactured-home placements must be greater than 20 years old, measured from the Washington Department of Labor and Industries approval date, and a used home moved in from elsewhere needs an L&I fire-life-safety inspection¹. Because the wording is easy to misread, confirm the exact requirement for your unit with Building & Planning before buying a home to move.

1. Ask Adams County Planning to identify the parcel's zoning district and confirm the use, minimum lot area, setbacks and site layout^2,11.
2. Confirm potable water and wastewater service; a residence needs a septic permit or Existing System Evaluation unless an available city or community sewer provides an availability letter⁸.
3. Resolve access with Public Works. New county construction needs a road-approach permit and Fire Marshal approval; state-highway access needs state approval⁸.
4. Prepare the application, site plan, complete construction drawings, design criteria and fee information; incomplete submittals are not accepted¹.
5. Submit to Building & Planning and complete inspections through the construction phases⁹.
6. If the site lies in a frequently flooded area within shoreline jurisdiction, meet the county flood-hazard provisions before development¹⁶. Ask Building & Planning whether the project needs a certificate of occupancy because we could not confirm a general county rule.

Start with zoning, legal access, water and septic rather than relying on the listing description. Adams County publishes a zoning map and code, while Environmental Health evaluates sewage issues for land development^12,17. A private-well permit or approval path could not be confirmed, so ask Environmental Health and the applicable state water office before assuming a well can serve the parcel.

Check the driveway early. A county driveway may serve no more than 2 residences; one longer than 150 feet must be at least 20 feet wide with an approved fire-apparatus turnaround, while one shorter than 150 feet must be at least 16 feet wide¹. Development in frequently flooded areas within shoreline jurisdiction must follow county flood-hazard provisions¹⁶. A short-term rental also needs county review, a safety inspection and compliant sewer or septic service⁵. The effective property-tax rate is about 0.8%, and the median annual bill is about $2,104¹⁵.