Accessory Structures in Lynnwood, WA

Lynnwood maintains 115 local ordinances across all categories, and 3 of those deal specifically with accessory structures. Here is a breakdown of what the city actually requires, what is prohibited, and where Lynnwood falls on the strict-to-permissive spectrum compared to other cities.

Shed & Carport Rules

Lynnwood splits residential accessory buildings into Type 1 (one per unit, 64 square feet, 8-foot height limit, 1-foot interior setback) and Type 2 (unlimited number, 480 square feet each, 15-foot height, 5-foot interior setback) under LMC 8.30.0810.

Key details: Type 1 footprint: 64 sq ft, one per unit. Type 2 footprint: 480 sq ft per unit, unlimited count. Type 1 height limit: 8 feet. Type 2 height limit: 15 feet. Type 1 / Type 2 interior setback: 1 ft / 5 ft.

An accessory building that exceeds the 64-square-foot Type 1 footprint without meeting Type 2 standards, or that violates the required street or interior setback, is a Unified Development Code violation. The development and business services department can issue a notice of violation and corrective order under LMC Chapter 1.40, with civil penalties starting at $100 the first day and climbing to $500 per day until the structure is brought into compliance, plus a property lien for penalties unpaid after 30 days.

ADU Rules

Lynnwood defines an accessory dwelling unit (ADU) as 1,000 square feet or less, either attached (AADU) or detached (DADU), under LMC 8.99.0250(A), and permits ADUs by right in the RN, RM-45, NC, and CDM zoning districts per the Title 8 use table.

Key details: Maximum ADU size: 1,000 square feet or less. ADU types recognized: AADU (attached) and DADU (detached). By-right zones: RN, RM-45, NC, CDM. State law floor: HB 1337 (2023) requires 2 ADUs/lot.

Building or occupying an ADU that exceeds the 1,000-square-foot size definition, or placing one in a zoning district where the use table does not permit ADUs, is a Unified Development Code violation. The city can issue a notice of violation and corrective order under LMC Chapter 1.40, with civil penalties starting at $100 the first day and rising to $500 per day until the violation is corrected, and a possible lien on the property for penalties unpaid after 30 days.

ADU Impact Fees

Lynnwood charges a park impact fee on every new accessory dwelling unit because the city's Table 3.104.030 fee schedule classifies ADUs as residential multifamily housing for PIF purposes, not as a free-standing single-family addition. Under the 2026-2027 rate table that classification currently sets the per-unit fee at $5,007.62, due before the city issues a building permit.

Key details: PIF rate for ADUs: $5,007.62 per unit. Classification: Residential multifamily (Note 2). Single-family rate (comparison): $6,969.54 per unit. Admin fee: $300.00. Rate period: Jan 1, 2026-Dec 31, 2027.

A permit applicant cannot obtain a building permit for an ADU without paying the assessed park impact fee, since the PIF is collected as a condition of development approval under LMC 3.107.050. An owner who disputes the standard multifamily rate may request an independent fee calculation for a $300.00 fee, or request a payment deferral for a $300.00 administrative fee, but cannot avoid the underlying $5,007.62 assessment by classifying the ADU as single-family.

The Bottom Line

Lynnwood's accessory structures rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Lynnwood is broadly strict or permissive.

This guide is based on Lynnwood's current municipal code. Local rules can and do change, so check the individual ordinance pages for the latest details, penalties, and FAQs.