Mason County, WA Building Safety: Fire Sprinkler Requirements (2026)

Mason County Code Chapter 14.17, Standards for Fire Apparatus Access Roads, ties a residential sprinkler mandate to road geometry rather than building size alone. Section 14.17.110 requires an automatic fire sprinkler system on new or existing fire apparatus access roads serving new residential or new commercial construction whenever the road exceeds 12 percent grade and lies more than 150 feet from the primary access point where it meets a county or state road right-of-way. Plans for the access road, and by extension the triggered sprinkler system, must be submitted to the fire marshal for review and approval under Section 14.17.020, and the fire marshal may require additional fire protection under Section 14.17.150 where topography or waterways prevent the road from meeting standard width, turning-radius or grade requirements.

Section 14.17.130 allows the fire marshal to modify other access-road standards, such as width or turnaround requirements, once a building is completely protected by an automatic sprinkler system, an offsetting benefit for installing one voluntarily. For subdivisions served by Group A community water systems, Mason County Code Section 14.18.030 separately lets the fire-suppression water storage requirement drop from 120,000 gallons to a minimum of 60,000 gallons where governing covenants require every residence to carry an internal fire sprinkler system, with further reductions for Firewise design.

The fire marshal reviews sprinkler and access-road compliance case by case and assesses a site-inspection fee under the county's adopted fee schedule for the required preliminary inspection.