Accessory Structures in Marysville, WA: What Residents Actually Need to Know

If you live in Marysville or are thinking about moving there, accessory structures are one of those things you probably won't think about until they affect you directly. Marysville has 3 specific rules on the books covering different aspects of accessory structures, and some of them might surprise you.

Shed Rules

Sheds and detached accessory structures must comply with MMC Ch. 22C.180 (Accessory Structures) and the Washington State Building Code (WAC 51-50). Permit requirements depend on size; small structures may be exempt from a full building permit but must still meet setback requirements. Contact the Permit Portal.

Key details: Code: MMC Ch. 22C.180; WAC 51-50. Setbacks: Must comply with residential zone requirements. Permit: Check with building dept. for size threshold. Contact: permits.marysvillewa.gov.

Unpermitted structures receive a notice to either obtain a retroactive permit (with double fees) or remove the structure within 60 days. Fines of $100–$500 apply for non-compliance.

Garage Conversions

Garage conversions to habitable space or ADUs require a building permit under WAC 51-50 and MMC. HB 1337 (2023) facilitates conversions to ADUs, allowing conversions even from existing structures that violate current setback or lot coverage rules. Contact the permit office for guidance.

Key details: Permit Required: Yes — building permit. ADU Conversion: Facilitated by HB 1337 (2023). Existing Structure Exemption: HB 1337 allows conversion from non-conforming structures. Contact: permits.marysvillewa.gov.

Unpermitted garage conversions face fines of $500–$2,000, mandatory permit acquisition (double fees), and may need to be restored to garage use if code requirements cannot be met.

ADU Rules

Marysville City Council adopted an interim ordinance on June 23, 2024, to comply with state HB 1337, allowing up to 2 ADUs per single-family lot. Final regulations are expected in fall 2025. HB 1337 requires: min. 1,000 sq ft ADU; 24 ft height minimum; no owner-occupancy required; impact fees capped at 50% of principal unit. Building permit required.

Key details: State Mandate: HB 1337 (2023) — RCW 36.70A.680. Interim Ordinance: Adopted June 23, 2024. Maximum ADUs: 2 per single-family lot. No Owner-Occupancy: Required (HB 1337 preempts).

Unpermitted ADUs face stop-work orders and removal or legalization requirements. Fines of $500–$2,000 apply for unpermitted construction. Properties with illegal ADUs may face title issues at sale.

The Bottom Line

Marysville'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 Marysville is broadly strict or permissive.

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