Home Remodeling in
Rainier, WA

Rainier's code, section 18.44.110, allows two ADUs per lot of record, each up to 1,000 square feet of habitable floor area. ADUs are left out of residential density calculations, and an existing structure can be converted into one.

An ADU needs an administrative use permit in the zones where it is allowed, on top of the building permit, so build that step into the schedule.

Rainier allows a recreational park trailer to serve as an ADU if it is at least 10 feet wide, no more than 10 years old when installed, and has a roof pitch of at least 3:12.

It also has to be permanently anchored to the manufacturer's instructions or an engineer's design, skirted all the way round, certified by the building official as meeting residential fire and life safety standards, and compliant with the state energy code and whole-house ventilation rules.

That route can cost less than a site-built cottage, but the foundation, skirting and energy work are real construction, so budget for them.

The code rules out ADUs on lots that are not on public sewer and cannot support the extra use with a septic system. It also rules them out in residential zones of one home per acre or less that fall within wetlands, fish and wildlife habitat, flood plains or geologically hazardous areas.

Building permit applications go in at City Hall, 102 Rochester Street West. The office is open Monday to Thursday, 8 a.m. to 5 p.m., on (360) 446-2265.