Redmond ADU rules

✓ Verified against code · August 19, 2026

Current rules under RZC 21.04.1110 (Redmond Zoning Code, post-Redmond 2050 restructure), adopted by Ordinance 3220 (recodification); Ord 3261 pending codification, in effect since June 28, 2025. The Redmond 2050 restructure (Ord 3220, effective June 28, 2025) moved ADU rules from RZC 21.08.220 to RZC 21.04.1110 — any source citing the old section number predates the current code. Ordinance 3261 (adopted June 2026) amends the ADU sections further and is pending codification; we re-check on every verification pass.

Common questions, answered from the code

Can I put a tiny home on wheels on my Redmond lot as an ADU?

Yes — Redmond explicitly names tiny homes as an ADU type, capped at 400 sq ft, with the trailer base screened by landscaping if publicly visible. Most guides answer 'no, tiny homes on wheels are RVs' — that's the generic rule; Redmond carved an exception. This is one of the most commonly wrong AI answers we track.

RZC 21.04.1110.C.2.c · Permalink

How big can a Redmond ADU be?

1,000 sq ft, with two exception paths: an attached ADU occupying an entire existing floor, or a lot over 10,000 sq ft where the ADU is affordable or provides a public benefit.

RZC 21.04.1110.C.3 · Permalink

Do I need parking for a Redmond ADU?

No — the minimum is zero everywhere in the city, in all three of the code's location categories.

RZC 21.40.010 Table D · Permalink

Where are Redmond's ADU rules actually codified?

RZC 21.04.1110, as of the June 2025 Redmond 2050 restructure. Sources citing RZC 21.08.220 are reading the retired code. Note also that Ordinance 3261 (June 2026) amends these sections and is pending codification.

RZC 21.04.1110 (Ord 3220) · Permalink

How tall can a Redmond DADU be?

Up to the zone maximum — 38 ft base in Neighborhood Residential — because structures containing ADUs are exempt from the 22-ft accessory-structure cap. That's the most generous DADU height in the region.

RZC 21.04.1120.C.1; Table 21.08.200.B · Permalink

The rules at a glance

ADUs allowed per lot	Two ADUs or tiny homes per residential lot — attached (within or added to the primary home) or detached, in any mix.RZC 21.04.1110.C.1, C.2.a
Maximum size	1,000 sq ft total (the state-law floor, exactly). The Administrator may allow more if the ADU occupies an entire single floor of the primary unit, or on lots over 10,000 sq ft where the ADU is affordable or provides a public benefit. Tiny homes max 400 sq ft.RZC 21.04.1110.C.3.a–d
Detached ADU height	Structures containing ADUs may go to the underlying zone maximum — 38 ft base in Neighborhood Residential — rather than the 22-ft cap that applies to other accessory structures.RZC 21.04.1120.C.1; Table 21.08.200.B
Detached ADU setbacks	Zone setbacks apply (NR: front 10 ft, street side 10 ft, interior side 3 ft, rear 5 ft, alley 2 ft) — and a detached ADU may sit immediately on a lot line that abuts a public alley or right-of-way. No accessory structures in the front setback.Table 21.08.300.A; RZC 21.04.1120.C.4–5
Off-street parking	Zero. The parking table sets ADU minimums at 0 in all three location categories — near transit, in centers, and everywhere else. No transit-proximity condition needed.RZC 21.40.010 Table D
Owner-occupancy	None. No owner-occupancy provision exists anywhere in the current chapter.RZC 21.04.1110 (absence verified)
Lot coverage / floor area	The DADU and the primary unit must each meet zone lot coverage (NR 50%; 60% for lots ≤18,000 sq ft with 3+ units). NR also caps total gross floor area of all structures by unit count — 4,500 sq ft for one unit, 6,000 for two, 7,500 for three — which effectively binds the combined house-plus-ADU size.Table 21.08.200.B–.C; RZC 21.04.1120.C.2.a
Permit path & timeline	Permitted outright in NR, NMF, NMU and mixed-use zones — a residential building permit only, no land-use permit. No city-published ADU timeline; secondary sources suggest roughly 4–8 weeks.RZC 21.04.0100; redmond.gov/469

Worth knowing

Redmond is a rare explicit-yes city for tiny homes on wheels: they count as an ADU type (max 400 sq ft), with the trailer base landscape-screened if visible from public view.
Fire sprinklers are required for new detached ADUs.
A home business inside a detached ADU has no size restriction — unusual.
The NR total-floor-area schedule (6,000 sq ft at two units) can bind before lot coverage does on large-house lots.

On our watchlist

Ordinance 3261 (adopted June 2, 2026) — the 2025 Legislative Conformance package — amends RZC 21.04.1110/21.04.1125 (parking, permitting timelines, conversions) and is pending codification. We re-check each pass and will log the changes the day they publish.

Check your parcel

The rules above are citywide — what you can build depends on your lot’s zone, size, and setbacks. Look yours up on the official viewers:

Primary sources

Other Washington cities

Bellevue · Bothell · Burien · Edmonds · Everett · Issaquah · Kent · Kirkland · Lynnwood · Olympia · Renton · Sammamish · Seattle · Shoreline · Tacoma

Not legal advice. Every fact above cites the code section it comes from — check the cite, or ask your city’s planning department to confirm your specific lot. Spotted an error or a new ordinance? See about to reach us; corrections are logged in the changelog.