Mason County, WA Building Safety: Building Permits (2026)

Mason County Code Section 14.08.030 amends IBC/IRC Section 105.1, Permits Required, adding categories the county specifically calls out beyond the base International Building and Residential Codes it adopted at Section 14.04.010. Permits are required for all docks, piers, and floats, except normal maintenance and repair of boathouses and detached, chain-anchored floats under one hundred twenty square feet. Any seawall, bulkhead, or similar shoreline structure needs a permit regardless of construction material, whether rock, rip rap, pilings, wood, or concrete block. Permits are also required for park trailers, recreational park trailers, manufactured housing, commercial structures, commercial coaches, and factory-built housing, and for the construction of any vehicular or pedestrian bridge, with plans for a bridge stamped by a Washington-licensed engineer unless the building official approves a small private footbridge without engineer review.

A separate Tenant Review Application permit is required for commercial buildings whenever the tenant changes before occupancy, whether or not construction is performed, and for each individual tenant space in a shell building finished at a later date; the fee follows the county's adopted building permit fee schedule under Chapter 1.10. Applications and fees go through the Mason County Department of Community Development, and once issued a permit expires under Section 14.08.040, after which resuming work requires a new permit at half the original fee if no plans have changed and the lapse has not exceeded one year.