Lacey, WA Accessory Structures: ADU Rules (2026)
ADU rules in Lacey, WA, also called accessory dwelling unit regulations or granny flat ordinances, cover setbacks, owner-occupancy, parking, and permit requirements.
Key Facts
- Maximum size
- Fifty percent of main unit, not over 850 square feet
- ADUs per lot
- One, in addition to the single-family dwelling
- Density
- An ADU does not count as a dwelling unit
- Parking
- At least one parking space should be provided
- Detached single-story setbacks
- Front sixteen feet, side five feet, rear five feet
- Design review
- Required for accessory structures needing a building permit
Summary
In the City of Lacey, Washington, an accessory dwelling unit is limited to fifty percent of the main unit and no more than eight hundred fifty square feet of floor area, and a lot gets only one ADU in addition to the single-family dwelling. An ADU does not count as a dwelling unit for density, must read as subordinate to the house, and needs a pedestrian walkway and at least one parking space.
B. Design Requirements. ... In order to assure that the development of all accessory dwelling units and those accessory structures to which this section is applicable is consistent with policies of the Comprehensive Land Use Plan, the following special design features and provisions shall apply to all accessory dwelling units: 1. Size. An accessory dwelling unit shall be limited in size to fifty percent of the size of the main unit and not to exceed eight hundred fifty square feet in floor area, except as provided in subsection C of this section. 2. Density Calculations. For the purposes of calculating residential density, accessory dwelling units shall not count as a dwelling unit. 3. Only One ADU per Lot Permitted. There shall not be more than one accessory dwelling located on a lot in addition to the single-family dwelling. ... 9. Parking. ... At least one parking space should be provided for the accessory dwelling unit. ... 10. Pedestrian Access. A pedestrian walkway from the street or alley to the primary entrance of an accessory dwelling unit shall be provided.
Full Breakdown
The City of Lacey defines an accessory dwelling in LMC 16.06.055 as a separate living unit (apartment) integrated within a single family dwelling, or a detached unit on the same lot as a single family dwelling. LMC 14.23.071 sets the design criteria that apply to every one.
Size is capped at fifty percent of the main unit and eight hundred fifty square feet of floor area. Only one accessory dwelling is allowed on a lot in addition to the single-family dwelling, and it does not count as a dwelling unit when residential density is calculated. The administrator can allow a larger unit under subsection C, for example when the ADU sits inside the existing main unit such as a basement, and every request must meet three mandatory criteria: subordinate to the main unit, no discernable neighborhood impact, and the least size necessary. Size can also be reduced when the full size would compromise the design standards.
The unit must be clearly subordinate. An integrated ADU must present the appearance of an individual single-family residence, and designs that give the impression of a duplex are not permitted. A detached ADU sits in a less dominant position on the lot, and one above a garage must complement the main residence. The driveway to a detached unit is consolidated with the existing driveway, and exterior materials and colors complement the primary residence. A pedestrian walkway from the street or alley to the primary entrance is required, and at least one parking space should be provided. Accessory structures needing a building permit require design review.
Setbacks come from the zone. In the Low Density Residential District, LMC 16.13.050 sets single-story detached ADU minimums at sixteen feet front, five feet side, five feet rear and ten feet on a flanking street; a taller detached ADU needs ten feet on the side and rear. Maximum height for the main building and accessory dwelling is twenty-five feet, or thirty-five feet with a roof pitch of at least four feet vertical to twelve feet horizontal.
Violations & Fines
Zoning in Title 16 and the Title 14 building and design standards are regulations enforced civilly under LMC 14.40.020, so an ADU built outside these standards faces a notice of civil violation: $100 for the first day, $200 for the second, $300 for the third, $400 for the fourth and $500 per day after four days, plus the city's abatement costs. A violation of any Title 14 provision is also a misdemeanor under LMC 14.17.080, punishable by a fine of up to $5,000 and/or imprisonment of up to one year.
Frequently Asked Questions
How big can an ADU be in Lacey?
Can I build two ADUs on one lot in Lacey?
Does an ADU count toward density in Lacey?
What setbacks apply to a detached ADU in Lacey?
Is parking required for an ADU in Lacey?
Sources & Official References
Other rules in Lacey
How Lacey compares: Easiest Cities to Build an ADU·Compare Lacey to another location·View the Washington accessory structures overview
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