Allentown, PA Fence Regulations: Retaining Walls (2026)

Under Chapter 350, § 350-7 (Site grading and retaining walls) of the City of Allentown's Land Development and Subdivision code, general site grading on any subdivision or land development must comply with § 355-10 of Chapter 355 (Land Development Controls), and projects must be designed and laid out to avoid excessive cut and fill. The retaining wall standard is more specific: any wall that will result in an exposed height of four feet or more, or that will be subject to loading by vehicular traffic (for example, a wall next to a driveway or parking area), must be designed by a professional engineer experienced in retaining wall design.

That engineering requirement applies regardless of wall material or location on the site once the four-foot exposed-height threshold or vehicular-loading condition is met. The code does not carve out a residential exemption from the engineering requirement itself. Beyond hiring an engineer, applicants must build the wall design into the land development submission in two stages. First, conceptual retaining wall designs must be included in the land development design drawings so the City can confirm the walls are dimensionally capable of being built within the limits of the development without impacting adjoining properties or the public right-of-way.

Second, the land development plans must carry a notation stating that detailed structural retaining wall design drawings will be submitted for review during the building permit stage, subject to approval by the City or the City's third-party plan reviewer. In practice this means retaining wall engineering is checked twice: once conceptually at land development plan approval, and again at the structural detail level when the building permit is pulled. The requirement is part of the broader site grading article, which also requires grading plans to conform to Chapter 355's controls and directs developers to avoid land that the City finds unsuitable due to flooding, improper drainage, steep slopes, rock formations, or adverse earth conditions unless mitigation measures are approved by the Planning Commission.