Can I build a backyard home in Clyde Hill?
Since 2023, Washington law lets most city lots hold up to two more homes. Clyde Hill 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 Clyde Hill allows.
The headline standards. Tap any one for the full wording and the code section.
ADUs per lot2: up to two ADUs on a lot with a single-family dwellingFull wording
2: up to two ADUs on a lot with a single-family dwelling; no ADU if the lot has a middle housing unit (CHMC 17.39.030).
Max size1,000 sq ft gross floor areaFull wording
1,000 sq ft gross floor area (CHMC 17.39.030).
Max height25 ftFull wording
25 ft (CHMC 17.39.030), the same as the R-1 principal building limit (CHMC 17.16.020).
Front setback30 ft in R-1 (same as the house)Full wording
Same as principal: 30 ft in R-1 (CHMC 17.16.040).
Side setback15 ft each side on lots of 15,000 sq ft+; less on smaller lotsFull wording
Same as principal: 15 ft each side on lots of 15,000 sq ft or more; 10 ft each side on lots over 10,000 and under 15,000 sq ft; 15 ft combined with 5 ft minimum on lots of 10,000 sq ft or less (CHMC 17.16.050).
Rear setback35 ft in R-1 (same as the house)Full wording
Same as principal: 35 ft in R-1 (CHMC 17.16.060). The reduced rear setback for small accessory buildings does not apply to ADUs. An ADU may be at the lot line next to a public alley that is not routinely snow-plowed (CHMC 17.39.030).
Lot coverage30% structural coverage and 60% impervious coverageFull wording
30% structural coverage and 60% impervious coverage (CHMC 17.16.080).
Parking2 per ADU on lots over 6,000 sq ft, 1 under; none near major transitFull wording
2 stalls per ADU on lots over 6,000 sq ft and 1 stall per ADU on lots under 6,000 sq ft, in addition to the principal dwelling's spaces. None within one-half mile walking distance of a major transit stop (CHMC 17.39.030).
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. Attached (AADU) or detached (DADU) ADUs are permitted in the R-1 zone (CHMC 17.39.010, 17.39.030), but not on lots with critical areas or their buffers (CHMC 17.39.030).
Minimum lot size
None stated for an ADU; the R-1 minimum lot area of 20,000 sq ft applies to new lots (CHMC 17.16.030).
Do you have to live there?
No. None stated in CHMC 17.39 as amended by Ord. 1019 (2025). The owner must record a registration agreeing to the ADU standards (CHMC 17.39.040).
Can it be sold on its own?
Not addressed; RCW 36.70A.681 floor applies
Pre-approved plans
Not confirmed yet — ask the city.
How long the city takes
Not published
Impact fees
Not found; RCW 36.70A.681 caps ADU impact fees at 50% of the principal unit's
Plans Clyde Hill has already approved.
A pre-approved plan skips the design review: Clyde Hill 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 Clyde Hill 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 Clyde Hill 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 Clyde Hill allows, what could fit, and a planning cost range. Free, no obligation.