Retaining walls across the DC area
When does a retaining wall need a permit or an engineer? The rules differ at every jurisdiction line. Here is the short answer for each.
Disclaimer: This is general information, not legal or professional advice for any one property. Codes change. SetbackIQ is not a zoning determination, a permit, or a survey, and it does not replace an architect, engineer, or lawyer. Confirm with your building and zoning offices before you build, buy, or sign a contract.
| Where | Short answer |
|---|---|
| Washington, DC | A retaining wall up to 4 ft, measured from the bottom of the footing, needs no building permit if it disturbs under 50 sq ft. Taller walls, walls with a surcharge, and walls in public space need permits. |
| Montgomery County, MD | A retaining wall up to 48 in, measured from the bottom of the footing, needs no permit unless it supports a surcharge. Retaining walls made necessary by street changes are exempt from setbacks. |
| Prince George's County, MD | Walls over 2 ft, or any wall supporting a structure, need a permit. Zoning caps retaining walls at 6 ft above finished grade (10 ft for foundations and driveways) and asks for 3 ft terraces between stacked walls. |
| Alexandria, VA | Walls over 5 ft need a soil report. 2 to 5 ft needs a detail package, a 1,500 psf design or a soil report. Walls up to 2 ft may stand in any yard. |
| Arlington County, VA | A wall holding back less than 3 ft of soil needs no building permit. Retaining walls count as obstructions in the corner triangle, and in an RPA any new or replaced wall needs county review. |
| Fairfax County, VA | A retaining wall holding back less than 3 ft of soil needs no building permit. Taller walls or walls with a surcharge do. Fairfax counts walls toward fence height limits, and marine clay or grading over 2,500 sq ft add engineering and plan review. |
Towns and cities inside these counties (for example, Rockville, Gaithersburg, Bowie, Laurel, Herndon, Vienna, and Falls Church) have their own rules.