Meets Base WA IRC R105.2 Dimensional Exemption (Subject to Local Setbacks & Site Overlays)
Unincorporated Clark County Base WA IRC R105.2 Dimensional Rule:
≤ 4.0 feet (48 inches) measured from the BOTTOM of the buried footing to the top of the wall (~3 ft visible above grass), with zero slope/driveway surcharge and ≥ 2x height horizontal spacing on terraced walls.
≤ 4.0 feet (48 inches) measured from the BOTTOM of the buried footing to the top of the wall (~3 ft visible above grass), with zero slope/driveway surcharge and ≥ 2x height horizontal spacing on terraced walls.
Local Setback & Municipal Note (Unincorporated Clark County):
Exempt ≤ 4.0 ft measured from bottom of footing to top of wall unless supporting a surcharge or terraced closer than 2H:1V.
⚠️ Informational Code Reference Only — Not an Official City Determination: Even when a deck, wall, shed, or fence meets the base WA IRC R105.2 dimensional threshold, local property-line setbacks, critical-area/wetland buffers, shoreline overlays (e.g., Kalama/Columbia/Lewis rivers), steep-slope geohazard zones, utility easements, separate electrical/plumbing permits, and HOA rules still apply. The property owner and contractor of record are solely responsible for verifying parcel rules with the local permit counter before work begins.
Frequently Asked Questions (Unincorporated Clark County, WA)
1. How tall can a retaining wall be without a permit in Unincorporated Clark County, WA?
In Unincorporated Clark County (WA IRC R105.2), a retaining wall up to 4.0 feet (48 inches) tall measured from the bottom of the footing to the top of the wall does not need a building permit, provided it does not support a sloped bank, driveway, or structure surcharge.
2. Can I build two 3.5-foot tiered retaining walls without a permit in Unincorporated Clark County, WA?
Only if the upper wall is set back horizontally at least 2 times the height of the lower wall (the 2H:1V rule, e.g., 7+ feet back). If terraced walls are placed closer together, Unincorporated Clark County treats them as one combined structural wall requiring engineering and a permit.