Building a Shed in Mountlake Terrace? Here's What You Need to Know

Mountlake Terrace is a south Snohomish County suburb with a notably strict permit exemption threshold. Only sheds under 80 square feet with walls no taller than 6 feet are fully exempt from a building permit — one of the lowest thresholds in the region. Sheds up to 200 square feet still qualify for a simplified shed permit. The maximum height is 25 feet, but any shed over 12 feet tall or 200 square feet must meet exterior design standards. Setbacks vary by zone — typically 5 to 15 feet for rear yards. Here's what the Mountlake Terrace code says.

Building Codes & Permits in Mountlake Terrace

Shed Permit RulesCity of Mountlake Terrace
Fully Exempt (No Permit)80 sq ft max, 6 ft wall height max
Shed Permit (Simplified)Up to 200 sq ft — simplified shed permit process
Max Shed Height (Overall)25 ft (design standards apply above 12 ft)
Setbacks (Side)5 ft to 10 ft (varies by zone)
Setbacks (Rear)5 ft to 15 ft (varies by zone)
Setbacks (Front)15 ft to 20 ft — not permitted in front setback

Sheds over 12 ft in height or 200 sq ft in area must meet exterior finishing/design requirements.

If a shed is within 5 ft of another structure, walls require fire-rated protection (gypsum wallboard). Eaves within 5 ft setback cannot have venting — roof venting only.

From the Municipal Code

One-story detached accessory structures used as tool and storage sheds, playhouses and similar uses are exempt from permits if the floor area does not exceed 80 square feet and no side wall exceeds 6 feet in height.

MTMC 15.05 — Permit Exemption

What You Need to Know

  • Strict exempt threshold (MTMC 15.05): Only 80 sq ft with 6 ft walls is fully exempt from permits — much lower than most cities. Sheds up to 200 sq ft qualify for a simplified shed permit.
  • Design standards (Shed Guidelines): Any shed over 12 ft in height or 200 sq ft in area must feature exterior finishing that meets city design requirements. This favors custom-built sheds with proper siding over kit sheds.
  • Fire separation (Shed Guidelines): If your shed is within 5 ft of another structure, the walls closer than 5 ft require fire-rated gypsum wallboard. Eaves within the 5 ft setback cannot have bird block venting — must vent through the roof only.
  • Setbacks vary (MTMC 19.30): Rear setbacks range from 5 to 15 ft, side setbacks from 5 to 10 ft depending on your zone. Front setbacks are 15 to 20 ft — sheds are not permitted in front yard setback areas.
  • Outside city limits? If your property is in unincorporated Snohomish County rather than within Mountlake Terrace city limits, Snohomish County rules apply instead.
  • Utilities: Even if the structure is exempt, any electrical or plumbing work requires a separate trade permit.

Have questions about permits or zoning? We don't have all the answers, but we deal with this stuff regularly and can usually help you figure it out. Reach out with your address and we'll point you in the right direction.

Building codes and permit requirements are subject to change. Contact your local building department to verify current regulations before beginning your project.

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