Can I build a backyard home in Covington?
Since 2023, Washington law lets most city lots hold up to two more homes. Covington 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 Covington allows.
The headline standards. Tap any one for the full wording and the code section.
ADUs per lot2 — any combination of attached or detachedFull wording
2 — any combination of attached or detached (CMC 18.35.335(2)).
Max size1,000 sq ft maximum floor areaFull wording
1,000 sq ft maximum floor area; no limit if the ADU is wholly within a basement or attic (CMC 18.35.335(5)(a)).
Max height24 ftFull wording
24 ft (CMC 18.35.335(5)(b)).
Front setback10 ft in R-6, 20 ft of driveway to a garage (same as the house)Full wording
Same as principal: 10 ft street setback in R-6, with 20 ft of driveway before a garage (CMC 18.30.030; 18.35.335(5)(c)).
Side setback7.5 ft interior setback in R-4, R-6 and R-8 (same as the house)Full wording
Same as principal: 7.5 ft interior setback in R-4, R-6 and R-8 (CMC 18.30.030; 18.35.335(5)(c)).
Rear setback7.5 ft in R-6 (same as the house); 0 ft at an alleyFull wording
Same as principal: 7.5 ft interior setback in R-6. A detached ADU may be built to a property line that abuts an alley, but not an access tract (CMC 18.30.030; 18.35.335(5)(c)).
Lot coverage70% maximum impervious surface in R-6Full wording
70% maximum impervious surface in R-6 (55% in R-4, 75% in R-8) (CMC 18.30.030); the table has no separate building-coverage cap.
Parking0 spaces for the first ADUFull wording
0 spaces for the first ADU; 1 space for a second ADU unless it is within 1/2 mile walking distance of a major transit stop (CMC 18.35.335(6)).
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 — ADUs are permitted on all residentially zoned lots regardless of lot size, attached or detached (CMC 18.35.335(1)-(2)).
Minimum lot size
None — ADUs are allowed on all residentially zoned lots regardless of lot size (CMC 18.35.335(1))
Do you have to live there?
No — the owner is not required to live in either unit (CMC 18.35.335(3)(a)).
Can it be sold on its own?
Yes — an ADU may be sold separately if it meets code and the property is divided under the Condominium Act (ch. 64.34 RCW) or another land division process (CMC 18.35.335(4)).
Pre-approved plans
None found
How long the city takes
Not published; ADU permits follow the same procedures and timelines as principal dwellings (CMC 18.35.335(14)).
Impact fees
Assessed under CMC Title 19, Impact Fees (CMC 18.35.335(15)); RCW 36.70A.681 caps ADU impact fees at 50% of the principal unit's.
Plans Covington has already approved.
A pre-approved plan skips the design review: Covington 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 Covington 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 Covington 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 Covington allows, what could fit, and a planning cost range. Free, no obligation.