Can I build a backyard home in Gig Harbor?
Since 2023, Washington law lets most city lots hold up to two more homes. Gig Harbor writes its own rules on top. Here’s what the code says, in plain English — and a free report on what may fit on your lot.
What Gig Harbor allows.
The headline standards. Tap any one for the full wording and the code section.
ADUs per lot2 per principal dwelling unit, any mix of attached/detachedFull wording
2 per principal dwelling unit, any mix of attached/detached; exempt from zone density limits (GHMC 17.69.030(A)(2)).
Max size1,200 sq ft (garage not counted)Full wording
1,200 sq ft gross floor area, measured finished wall to finished wall, excluding any related garage (GHMC 17.69.030(A)(4)); minimum is the state building code minimum (GHMC 17.69.030(A)(5)).
Max heightNot confirmed yet — R-1 caps buildings at 35 ftFull wording
Not confirmed yet — ask the city. (GHMC 17.69 sets no ADU height; R-1 caps all buildings at 35 ft under GHMC 17.16.070, subject to GHMC 17.99 design standards and the GHMC 17.62 height restriction area).
Front setback20 ft in R-1 (same as the house)Full wording
Same as principal: 20 ft in R-1 (26 ft to a garage, 12 ft to a porch) (GHMC 17.69.030(A)(6); GHMC 17.16.060(C)).
Side setback8 ft in R-1 (same as the house)Full wording
Same as principal: 8 ft in R-1 (GHMC 17.69.030(A)(6); GHMC 17.16.060(E)).
Rear setback30 ft in R-1 (same as the house)Full wording
Same as principal: 30 ft in R-1 (GHMC 17.69.030(A)(6); GHMC 17.16.060(D)); accessory-structure setbacks do not apply; no alley rule found.
Lot coverage40% hard-surface coverage in R-1Full wording
40% hard-surface coverage in R-1 (GHMC 17.16.060(F)).
Parking1 per ADU, on top of the house’s; none near major transitFull wording
1 off-street space per ADU in addition to the primary dwelling's (GHMC 17.72.030 table); none within 1/2 mile of a major transit stop (GHMC 17.69.030(A)(7)).
Where a city figure reads stricter than the state floor (RCW 36.70A.681), the floor may control — the report flags it for your parcel.
Living there, selling it, plans, time and fees.
Each answer is the code’s own wording, with the section it comes from. “Not published yet” means the city hasn’t posted a figure — the report asks the city, not the internet.
Are backyard homes allowed?
Yes — permitted outright in all residential zones that permit single-family homes; the ADU may be within, attached to, or detached from the principal dwelling (GHMC 17.69.030, 17.69.030(A)(1)).
Minimum lot size
7,200 sq ft in R-1 (7,500 sq ft for subdivision lots) — an ADU may be placed on any legal parcel meeting the zone's minimum lot size per building site (GHMC 17.69.030(A)(3); GHMC 17.16.060(A)).
Do you have to live there?
No — GHMC 17.69 contains no owner-occupancy requirement.
Can it be sold on its own?
Not addressed; RCW 36.70A.681 floor applies.
Pre-approved plans
None found (not mentioned on the city's Affordable Housing page, https://www.gigharborwa.gov/935/Affordable-housing).
How long the city takes
Not published
Impact fees
Not found in code; RCW 36.70A.681 caps ADU impact fees at 50% of the principal unit's. City's Affordable Housing page says it planned a 50% traffic impact fee cut for new affordable ADUs as part of a traffic impact fee update — adoption not confirmed.
Plans Gig Harbor has already approved.
A pre-approved plan skips the design review: Gig Harbor has already checked the drawings, so the permit review is about your lot.
Loading the plans…
Pictures are the official pages’ own. A pre-approved plan is not a permit: the city still reviews your site.
The code is half the answer. Your parcel is the other half.
Lines and easements
Where the lot lines really are, which setbacks apply on each side, and whether a utility or access easement takes the corner you had in mind.
Critical areas and slope
Steep slopes, wetlands and streams come with buffers that no citywide number shows. The report reads the county’s maps for your parcel.
Sewer, septic, water, trees
Whether sewer reaches the lot or it’s on septic, where the water service is, and which trees a city protects — the things that decide where a unit can actually go.
What Gig Harbor allows, what could fit on your lot, and a planning cost range. If something won’t fit, the report says so — and shows what might.
Where this page comes from.
Read from the Gig Harbor municipal code and the city’s own pages on November 5, 2026. The same table feeds the HousUp report, so the report and this page never disagree. Cities amend their codes; before you design anything, confirm the current wording with the city.
2 sources, read November 5, 2026
Find out what your property could become.
Type your address. Within a few hours: what Gig Harbor allows, what could fit, and a planning cost range. Free, no obligation.