Retaining Walls: Penn Hills vs Pittsburgh

Do I need a permit for a retaining wall in Allegheny County?

Allegheny County itself does not issue building permits — your township, borough, or city does, under the PA Uniform Construction Code (35 P.S. 7210.101). Under 34 Pa. Code Section 403.62(a)(13), a retaining wall 4 feet or less measured from the lowest grade to the top is exempt unless it supports a surcharge such as a driveway, building, slope, or pool. Walls over 4 feet, or any wall with a surcharge, generally require a municipal building permit and engineered drawings.

What counts as a surcharge that makes a small wall require a permit?

A surcharge is any added load behind the wall — a driveway, patio, building, swimming pool, fence, or a steep slope rising above the wall. In Pittsburgh's hillside neighborhoods and across the Mon Valley, even a wall under 4 feet often retains a slope or supports a structure, which removes the 34 Pa. Code 403.62 exemption. Confirm with your municipal building official before starting work.

When does the Allegheny County Conservation District get involved?

ACCD administers Pennsylvania's Erosion and Sediment Pollution Control Program under 25 Pa. Code Chapter 102 by delegation from PA DEP. A written E&S Plan is required for any earth disturbance of 5,000 square feet or more, and an NPDES Construction Stormwater Permit is required at 1 acre. Hillside retaining walls that involve significant cut and fill often hit these thresholds. Contact ACCD at 412-241-7645.

Do I need a permit for a retaining wall in Pittsburgh?

Yes, if the wall exceeds 4 feet in height from the lowest grade to the top. Walls under 4 feet are generally exempt unless they support additional loads.

Do I need an engineer for a retaining wall in Pittsburgh?

Retaining walls over 4 feet typically require engineered drawings from a licensed professional engineer registered in Pennsylvania.