Determine when a retaining wall triggers a building permit and engineered design under the International Residential Code (IRC)

Steps

1. Check wall height measured from the bottom of the footing to the top of the wall: under the IRC, retaining walls not exceeding 4 feet in that measurement are generally exempt from a building permit.
2. Note permit and engineering ARE required regardless of the 4-foot exemption if the wall supports a surcharge (slope, structure, driveway load) or impounds Class I/II/IIIA liquids.
3. For walls at or above 4 feet, obtain a design from a licensed professional engineer per IRC Section R404.4 (stability against overturning, sliding, and excessive foundation pressure, minimum 1.5 safety factor).
4. Check whether an engineered/manufactured SRW product installed per the manufacturer's instructions can substitute for a project-specific engineer stamp — many jurisdictions accept this, but confirm with the local building department.
5. Always confirm the exact threshold and process with the local Authority Having Jurisdiction, since many cities/counties adopt the IRC with local amendments that change the exempt height or add site-specific rules.