Lynnwood ADU rules
✓ Verified against code · August 19, 2026
Current rules under LMC Title 8 (Unified Development Code) — no standalone ADU section, adopted by Ordinance 3481 (amended by Ords 3492, 3507), in effect since July 1, 2025. Lynnwood didn't amend its ADU code — it replaced its entire development code. The 2025 Unified Development Code (Ord 3481) scrapped Titles 18/19/21, and ADUs are now regulated as ordinary dwelling units under a units-per-lot model, with the details still being amended by cleanup ordinances. Anything describing 'Lynnwood's ADU chapter' predates the UDC.
Common questions, answered from the code
Where are Lynnwood's ADU rules?
Nowhere singular — and that's the trap. The 2025 Unified Development Code has no standalone ADU chapter; ADUs are permitted-use dwelling units governed by the RN zone's units-per-lot rules, the parking exemption for sub-1,200 sq ft units, and a 1,000 sq ft cap in the definitions section. Guides citing the old Title 21 ADU chapter describe a repealed code.
LMC Title 8 (Ord 3481) · Permalink
How many ADUs can I add in Lynnwood?
Usually two — a house plus two ADUs hits the RN base of 3 units per lot. A fourth unit is possible with an affordable unit or within a quarter-mile walk of a major transit stop.
LMC 8.30 Table 8.30.03 · Permalink
Do I need parking for a Lynnwood ADU?
No. Units under 1,200 sq ft of gross floor area are exempt from parking citywide, and every conforming ADU (capped at 1,000 sq ft) qualifies.
LMC 8.40.0720(A) · Permalink
How tall can a detached ADU be in Lynnwood?
Up to the RN detached-configuration limit of 35 ft — a proposed ADU-specific 24-ft cap was dropped before adoption.
LMC 8.30 building-form tables · Permalink
Are Lynnwood's pre-approved DADU plans available?
Not yet. The program exists and designer submissions closed in July 2026, but the city hasn't published the plan sets. We'll log it in the changelog when they land.
City pre-approved DADU page · Permalink
The rules at a glance
| ADUs allowed per lot | No ADU-specific cap — the units-per-lot rules govern: RN zones allow 3 units per lot base (a house plus two ADUs), 4 with one affordable unit or within a quarter-mile walk of a major transit stop. ADUs are a permitted use in the RN, RM-45, NC, and CDM zones.LMC 8.30 Table 8.30.03; Table 8.35.01 |
| Maximum size | 1,000 sq ft — written into the ADU definition itself (a cap added by Ord 3492 in November 2025; the original UDC had none). No garage or storage exclusion is stated.LMC 8.99.0250 (Ord 3492 §18) |
| Detached ADU height | No ADU-specific limit — a proposed 24-ft ADU cap was dropped at adoption. Detached units fall under the RN detached-configuration maximum of 35 ft.LMC 8.30 building-form tables |
| Detached ADU setbacks | RN detached configuration: 10 ft from the street, 5 ft interior side and rear, 10 ft between buildings. No reduced alley setback — but where an alley exists, vehicle access must come from it.LMC 8.30 Tables 8.30.04–05 |
| Off-street parking | Zero. Dwelling units under 1,200 sq ft of gross floor area require no parking — which covers every conforming ADU, citywide, with no transit test.LMC 8.40.0720(A); Table 8.40.70 |
| Owner-occupancy | None — no owner-occupancy requirement exists anywhere in the adopted UDC. (Pre-UDC city guides described one; they're obsolete.)LMC Title 8 (verified absence) |
| Lot coverage / floor area | RN zones use FAR by unit count — 0.6 for one unit, 0.8 for two, 1.0 for three, 1.2 for four — plus building-footprint standards instead of lot coverage, and required amenity space (shared 10% of the lot or 120 sq ft private per unit at grade).LMC 8.30 building-form tables |
| Permit path & timeline | An ADU Permit is a Type 1a ministerial decision processed with the building permit — no notice, no hearing. Completeness review within 28 days; no codified final-decision deadline.LMC 8.90.0330; 8.90.0320 |
Worth knowing
- A pre-approved DADU plan program is in development — the designer-submission window closed July 2, 2026, but no plan sets are published yet.
- A proposed fire-sprinkler mandate for DADUs was rejected at adoption — it is not in the code.
- Edge case worth knowing: because ADUs count toward the 3-base/4-max units per lot, a lot that already holds two or more principal units can't always add two ADUs — a point of tension with the state statute's 'two ADUs per lot' that the city hasn't addressed publicly.
- Cleanup ordinances keep amending Title 8 (two in late 2025–2026 so far) — expect continued drift.
On our watchlist
Pre-approved DADU plan sets pending publication (submissions closed July 2026).
Ongoing UDC cleanup ordinances (Ords 3492, 3507, 3508 so far) keep amending Title 8 — we re-check the ADU-relevant tables each pass.
The draft fee schedule listed a $640 ADU permit fee; the adopted fee schedule is unverified.
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 · Olympia · Redmond · 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.