Bolthole Index

Grays Harbor County, Washington

Building permits, zoning and septic rules in Oakville, Washington

Oakville, Washington has adopted building codes and publishes a residential building-permit application through City Hall.12 Oakville sets zoning inside city limits; septic systems remain with Grays Harbor County Environmental Health.34 We could not confirm Oakville’s complete building-permit exemptions or general private-land RV occupancy rule; ask City Hall before planning construction or an RV stay.5

At a glance

Building permits
City residential application available; confirm project requirements with City Hall25
Zoning
Oakville’s own zoning districts and land-use table apply36
Septic permits
Grays Harbor County Environmental Health; design required with new applications47
RV living
General private-land occupancy unconfirmed; manufactured-home parks cannot accept RV residents8
Tiny homes
State building-code route exists; Oakville location and occupancy approval still need confirmation9
Accessory dwellings
One ADU on a qualifying lot; mobile homes or temporary structures need conditional-use approval10
Floodplain construction
Special flood hazard area standards include residential floor elevation above base flood elevation plus 3 feet11

Who to call

Building permits

Oakville City Hall — building and zoning inquiries

Residential building-permit application and City Hall contact for city building, zoning, water and floodplain questions

(360)273-8916

204 E Main Street | Oakville, WA 98568

Online permits →

Septic permits

Grays Harbor County Environmental Health Division — On-Site Sewage Section

Septic design, site evaluation, applications and permit/as-built records for Oakville properties using on-site sewage systems

(360) 249-5579

[email protected]

Online permits →

Contact details are copied from each office’s official page and were checked against it on October 11, 2026.

Off-grid gear

Going off-grid in Oakville means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in Oakville, WA?

Oakville has adopted the International Building Code and International Residential Code, including successor codes and amendments required by Washington law.1 Oakville’s residential application must be completed in full; incomplete applications will not be processed.2 Start with Oakville City Hall for your project’s building-permit requirements and exemptions, because we could not confirm a complete city requirement schedule.5 Washington’s optional small-project permit exemption applies only where the local government adopts it and all conditions are met; the exemption does not remove substantive building-code requirements.12

Who handles building applications in Oakville, and how do you reach them?

Contact Oakville City Hall at (360)273-8916 for the city’s residential building-permit application and questions about the proposed project.5 The city application asks for the parcel number or legal description, septic designer, water supply, sewage or septic arrangements, road access and whether the site is within a floodplain or prone to flooding.5 Prepare those details before submitting the application, and ask City Hall to identify the building official, required inspection stages and current building-permit fees for your work.5 Septic design and septic applications go separately to Grays Harbor County Environmental Health.47

Does Oakville have zoning, and what setbacks apply?

Oakville’s land-use table determines whether a proposed use is allowed in the parcel’s zoning district: P means permitted by right, C requires conditional-use approval, and a blank means the use is not allowed unless authorized as a temporary use.6 In Oakville’s residential district, accessory structures cannot occupy the front yard and must stay at least 5 feet from rear and side lot lines; accessory buildings next to a street must stay at least 15 feet from the side lot line abutting that street.13 Residential-district accessory structures have a maximum height of 22 feet; that limit does not establish the principal home’s height limit.14 Ask City Hall for the parcel’s district and principal-dwelling lot-size, coverage and setback requirements before drawing a site plan.5

How do septic permits work inside Oakville?

For an Oakville property using septic, Grays Harbor County Environmental Health administers on-site sewage systems, while the city handles its building application.42 Washington requires a septic permit before installation, repair, modification, connection or expansion, except for a minor repair.15 Grays Harbor County requires a Washington-licensed on-site designer or professional engineer and a design with every new septic application; applications go electronically through SmartGov, with paper accepted only for drawings.16 The county requires 2 test holes near the primary and reserve drainfield areas, each 2 feet wide and 6 feet deep with an access ramp.16 Grays Harbor County’s soil rating shows only 3.1% rated not limited for conventional drainfields; that countywide figure supports obtaining a site evaluation, not assuming an Oakville parcel cannot support septic.17

Can you live in an RV or tiny home in Oakville?

We could not confirm a general rule allowing residential RV occupancy on private land in Oakville; ask City Hall about the address, proposed duration and wastewater arrangements.5 Oakville’s manufactured-home parks cannot accept RVs for temporary or permanent residency.8 In Oakville’s special flood hazard area, RVs or travel trailers placed on a site for more than 180 days fall under the city’s flood-protection requirements; that threshold is not permission to live in an RV for a shorter stay.11 Washington recognizes code-compliant tiny houses of no more than 400 square feet, potentially on wheels, but local foundation, installation and location requirements still apply.9 Oakville allows one ADU on a lot with a single-family dwelling or designated manufactured home; an ADU using a mobile home or temporary structure needs a city conditional-use permit.10

What should you check before building a home in Oakville?

First, take the parcel and proposed use to City Hall to confirm zoning and building-application requirements.65 Next, establish water and wastewater arrangements: Oakville’s code states a $1,000 single-family city-water connection charge, but does not establish a universal connection requirement.18 For septic, arrange the licensed design and county site evaluation before committing the site to a house layout.16 Check flood exposure early: residential construction in Oakville’s special flood hazard area requires the lowest floor, including basement, above base flood elevation plus 3 feet, and a finished-construction FEMA elevation certificate before occupancy certification.11 Submit the completed city application and confirm the inspection schedule; Washington’s residential energy-code rules require final inspection and approval before occupancy.219 For land outside Oakville city limits, use the Grays Harbor County guide, where county zoning applies to unincorporated land.20

Watch-outs

  • Oakville’s accessory-structure setbacks do not establish the setbacks or minimum lot size for a principal home; ask City Hall for the parcel’s full district standards.135
  • Grays Harbor County does not currently require septic inspections for private-home sales, but lenders or real estate professionals may require a pumpers report; a sale is not proof that the existing system will support your project.21
  • Washington’s domestic groundwater exemption covers up to 5,000 gallons per day per project, but other water-law and local requirements still apply; submit Ecology’s drilling notice 72 hours before drilling and confirm Oakville’s private-well requirements with City Hall.225

Sources

  1. Title 15, Chapter 15.04, Section 15.04.010—Adoption of Uniform Codes (Oakville), quoted and re-checked
  2. Residential Permit (Oakville), quoted and re-checked
  3. Title 17, Chapter 17.16, Section 17.16.020—Interpretation of table of land uses (Oakville), quoted and re-checked
  4. Septic & Wastewater Systems, quoted and re-checked
  5. Oakville City Hall — building and zoning inquiries (oakvillecityhall.com)
  6. Title 17, Chapter 17.16, Section 17.16.020—Interpretation of table of land uses (Oakville), quoted and re-checked
  7. Septic & Wastewater Systems, quoted and re-checked
  8. Title 17, Chapter 17.16, Section 17.16.020—Interpretation of table of land uses (Oakville), quoted and re-checked
  9. Tiny Houses (Washington statewide rule), quoted and re-checked
  10. Section 17.28.010—Accessory dwelling units (Oakville), quoted and re-checked
  11. Section 14.08.140—Applicability (Oakville), quoted and re-checked
  12. WAC 51-16-080 — Permit exemptions guideline (Washington statewide rule), quoted and re-checked
  13. Section 17.28.020—Accessory structures (Oakville), quoted and re-checked
  14. Section 17.28.020—Accessory structures (Oakville), quoted and re-checked
  15. WAC 246-272A-0200 Permit requirements (Washington statewide rule), quoted and re-checked
  16. Grays Harbor County Environmental Health Division — On-Site Sewage Section (graysharbor.us)
  17. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  18. Section 13.04.260—Water meters—Installation—Charges (Oakville), quoted and re-checked
  19. WAC 51-11R-10500 — Section R105—Inspections (Washington statewide rule), quoted and re-checked
  20. Planning & Zoning, quoted and re-checked
  21. Septic & Wastewater Systems, quoted and re-checked
  22. Groundwater permit exemption (Washington statewide rule), quoted and re-checked

Written October 11, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

Answers from the rulebook for Oakville

Oakville’s own rules

  • Building code adoptedAdopted

    Construction inside Oakville city limits.

    • The adopted codes include successor codes and amendments mandatorily required by Washington state law.
    • The UPC provisions affecting sewers or fuel gas piping are not adopted under subsection E.
    “The following are adopted: A. International Building Code (The IBC) [...] B. International Residential Code (The IRC)”
  • Local zoningPresent

    Land inside Oakville city limits; Oakville has its own Title 17 zoning code and zoning-district land-use table.

    “Table 17.16.020-1. Table of Land Uses for all Zoning Districts”
  • Zoning districtsPublished

    Oakville zoning districts and land-use table.

    • The opened table identifies R, C, I, F/A, and R-2 district columns.
    • A blank table cell means the use is not allowed unless allowed as a temporary use under Section 17.04.190.
    • P means permitted by right; C means conditional-use approval is required.
    “The land use table in the UDC determines whether a specific use is allowed in a zone district. The zone district is located on the vertical column and the specific use is located on the horizontal row of these tables.”
  • SetbacksSpecified

    Accessory structures in Oakville's residential zoning district.

    • Accessory structures are not allowed in the front yard.
    • They must be at least five feet from rear and side lot lines.
    • An accessory building adjacent to a street must be at least 15 feet from the side lot line.

    rear and side lot-line setback: >= 5 feet · side lot line abutting a street: >= 15 feet (accessory building)

    “The location of accessory structures are not allowed in the front yard or within five feet from the rear and side lot lines; provided, however, that accessory buildings may not locate closer than fifteen feet to a side lot line that abuts a street;”
  • Building heightSpecified

    Accessory structures in Oakville's residential zoning district.

    • The cited limit applies to accessory structures, not necessarily the principal dwelling.

    maximum accessory-structure height: <= 22 feet

    “Accessory structures shall not exceed twenty-two feet in height;”
  • Camping on your landLimited

    Camping in Oakville city parks and cemeteries.

    • The prohibition applies at any time.
    • Remaining in a park or cemetery outside posted hours also requires prior written approval of the Director.
    • The section does not resolve camping on private land outside parks and cemeteries.
    “It is unlawful to camp in any cemetery or park at any time or to remain within any park or cemetery except during hours indicated as being the hours during which the site is open to the public without the prior written approval of the Director.”
  • Manufactured homesAllowed

    Designated manufactured homes in Oakville's zoning districts where the Title 17 use table marks the use P.

    • Manufactured-home parks in the residential zoning district must be at least one acre.
    • Each manufactured-home space must contain at least 2,500 square feet per unit.
    • Only one manufactured home is allowed per space.
    • Each space must have permanent sewer, water, and electrical connections.
    • A manufactured-home park requires an approved binding site plan obtained as part of a conditional-use permit.
    • Manufactured-home parks may not accept recreational vehicles for temporary or permanent residency.

    manufactured home park minimum area: >= 1 acre · minimum manufactured home space: >= 2500 square feet per unit

    “Manufactured homes, designated | P | P | 4”
  • Accessory dwellingsAllowed

    One accessory dwelling unit on a lot containing one single-family dwelling or designated manufactured home inside Oakville city limits.

    • One ADU is allowed per lot.
    • Maximum occupancy is two people in a 300-400 square-foot unit, three people in a 401-600 square-foot unit, and four people in a unit 601 square feet or larger.
    • An ADU using a mobile home or temporary structure requires a conditional-use permit from the City.

    ADUs per qualifying lot: 1 unit · 300-400 square-foot ADU occupancy: <= 2 people · 401-600 square-foot ADU occupancy: <= 3 people · 601+ square-foot ADU occupancy: <= 4 people

    “Any lot which contains one single-family dwelling or designated manufactured home may have one accessory dwelling unit (ADU) on a lot. The ADU may be in the primary residence or in an accessory structure.”
  • Mandatory utility hookupWater (with conditions)

    Properties inside Oakville's corporate limits seeking connection to the city water system.

    • The code establishes a single-family water connection charge of $1,000.
    • The cited section establishes connection charges but does not state a universal mandatory connection-distance rule or a sewer-connection requirement.

    single-family water connection charge: 1000 USD

    “As to properties located within the corporate limits at the time of the connection, the following connection charges shall apply: 1. Single-family residence. As to a water connection, the sum of one thousand dollars ($1,000.00).”
  • Building in a floodplainRequired

    New structures and substantial improvements in Oakville's special flood hazard area.

    • Requirements include new structures, substantial improvements, substantially damaged-building repairs, manufactured homes placed on a site, and RVs or travel trailers placed on a site for more than 180 days.
    • Residential structures must have the lowest floor, including basement, elevated above base flood elevation plus three feet.
    • Before certificate of occupancy, a current finished-construction FEMA elevation certificate is required.
    • Before certificate of occupancy, a signed recorded nonconversion agreement is required, subject to the four-foot-height waiver in Section 14.08.150(I)(4).

    residential lowest-floor elevation above base flood elevation: >= 3 feet · RV/travel-trailer placement threshold: > 180 days

    “The protection requirements of this article apply to all new structures and substantial improvements in the SFHA, which include: 1. Construction or placement of a new structure;”
  • Permit processPartial

    Oakville residential permit applications.

    • Applications must be completed in full.
    • Incomplete applications will not be processed.
    “Applications must be completed in full. Incomplete applications will not be processed.”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Oakville or Grays Harbor County directly.

  • Building permit — Building permits for construction inside Oakville city limits.
  • Owner-builder exemption — Owner-builder exemptions inside Oakville city limits.
  • Inspections — Building inspections inside Oakville city limits.
  • Certificate of occupancy — Certificates of occupancy inside Oakville city limits.
  • Minimum dwelling size — Minimum dwelling size inside Oakville city limits.
10 more unanswered
  • Minimum lot size
  • Lot coverage
  • Tiny homes
  • Off-grid sanitation
  • Well permit
  • Agricultural exemption
  • Subdividing land
  • Driveway access
  • Short-term rentals
  • Permit fees

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that Oakville publishes no rule on the point, not that none exists. Grays Harbor County’s page lists the county offices to call.

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