Olympia code lines we quote from
Olympia adopts the state building and residential codes through OMC 16.04.020, in their current state-adopted editions, and the chapter does not amend the residential list of work that needs no permit. That list treats a retaining wall not over four feet from footing to top as exempt, unless it carries a surcharge or holds back Class I, II, or IIIA liquids.
OMC 13.16.020 requires an engineering permit application before stormwater is discharged to the city storm drainage system, and OMC 13.16.010(E) counts clearing, grading, or filling as development with no minimum area. Olympia’s June 2023 guidesheet sets the review path by size: over 2,000 square feet of new or replaced hard surface brings an abbreviated plan, and over 5,000 square feet brings a full plan with a scoping meeting.
Steep ground carries a separate rule. OMC 18.32.610 treats a slope of 40 percent or steeper with at least 10 feet of vertical change as a landslide hazard, and OMC 18.32.630 sets the buffer at the larger of 50 feet or one-third of the slope height at the top edge, unless a geologist or geotechnical engineer recommends otherwise.
Nearby, we also build in Lacey, Tumwater, Yelm, and DuPont, and we serve the rest of western Washington.