Accessory Structures in Grays Harbor County, WA (2026)
3 rules for unincorporated Grays Harbor County, Washington.
Verified from official government sources
ADU Rules
Unincorporated Grays Harbor County does not zone for a standard accessory dwelling unit; instead it allows a temporary second dwelling for a family caregiver as a conditional use. County Code § 17.24.030(F) lets the board of adjustment approve one on any G-5 parcel under ten acres, restricted to a member of the property owner's family and subject to removal once the arrangement ends.
Temporary Second Dwelling Rules, Grays Harbor County
Significant RestrictionsGrays Harbor County Code § 17.24.030(F)
F.On any legal parcel which is less than ten acres, a second temporary dwelling unit may be authorized provided that the following conditions are met:(1)The accessory unit is for use by a member of the family of the occupants of the principal residence on the property. For the purposes of this section, "member of the family" means related by blood, marriage or law;(2)No division of the property...
ADU Impact Fees
Grays Harbor County does not charge a flat ADU impact fee; instead it converts accessory dwelling units into Equivalent Residential Units for both the one-time general facility charge and the monthly water/sewer bill, adding a full ERU once the ADU passes 600 square feet.
ADU Water/Sewer Fees in Grays Harbor County
Some RestrictionsGrays Harbor County Code § 13.22.120(C)
For the purpose of determining general facility charges for water and sewer capacity, the county hereby determines Equivalent Residential Unit (ERU) values based on the following: ... C.Each accessory dwelling unit greater than six hundred s.f. = one ERU.
Shed & Carport Rules
A detached tool shed or playhouse under 200 square feet does not need a county building permit in unincorporated Grays Harbor County, but it must still meet Title 17 zoning setbacks and Title 18 critical area rules; anything larger needs a permit from the building official.
Shed Permit Rules in Grays Harbor County
Light RestrictionsGrays Harbor County Code § 15.04.020(K), item (1) (IBC § 105.2)
Permits shall not be required for the following: ... Building: ... (1)One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses, provided the floor area does not exceed two hundred square feet, and provided the structure complies with the building setback requirements set forth in Title 17 of this code governing zoning and Title 18 of this code governin...
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