Home Remodeling in
Yelm, WA

This is the rule that makes Yelm different from its neighbors. In the moderate-density residential R-6 district, one secondary dwelling unit may be created on a single-family lot, and the size cap is tied to the lot rather than the main house.

For lots of record under one acre, the conversion or addition may not exceed 1,000 square feet. For lots of record of one acre or more, it may not exceed 1,500 square feet.

Compare that with Lacey, where the cap is the smaller of a fixed figure or half the size of the main house. If you own acreage in Yelm, you may have more room to work with than the same budget would buy you closer in.

The allowance is also subject to the availability of public utilities, and has to comply with building, plumbing, fire and other applicable codes. On larger prairie lots the utility question is not a formality.

Yelm's Planning and Building Division processes and issues the permits required under the Washington State Building Code and the Growth Management Act, with local rules set out in the Yelm Unified Development Code at Title 18 YMC.

Staff are in the Public Services building at 901 Rhoton Road NW, not at City Hall, and the phone number is (360) 400-5003. Business hours run 7:00am to 5:00pm Monday to Friday, which is an earlier start than most of the county and useful if you want to catch someone before a work day.

Yelm has also been amending its development code, including Ordinance No. 1154 which set design standards for unit lot subdivisions and accessory dwelling units.

HB 1337 requires jurisdictions planning under the Growth Management Act to allow two accessory dwelling units per lot inside urban growth areas, prohibits capping an ADU below 1,000 square feet, and prohibits owner-occupancy requirements. Those requirements have applied since 30 June 2026, and they override any local rule that conflicts.

Yelm's published R-6 standard describes one secondary unit. As with the rest of the county, the sensible move is to confirm the currently adopted standard with Planning and Building rather than designing to a figure found online.