Lower Merion, PA Building Setbacks & Zoning: Lot Coverage Limits (2026)

Section 155-3.4, Lot occupation, requires every lot to conform to the minimum lot width and area of its underlying district and to locate buildings on the lot as specified in that district's form table, with the minimum lot width measured parallel to the street at the point of the proposed building closest to the street. Table 4.1.1, LDR1 Dimensional Standards, then sets the actual numbers for the Township's largest-lot residential district: a 200-foot minimum lot width, a 90,000-square-foot minimum lot area, and an impervious surface cap of 20% maximum, meaning driveways, patios, walkways, pools, and building footprint together cannot exceed one-fifth of the lot.

That impervious limit rises slightly by district: LDR2 allows 21% impervious surface on a smaller 45,000-square-foot minimum lot, illustrating that the Township scales its coverage cap to lot size rather than applying one flat percentage Townshipwide. The same table also sets front, side, and rear setbacks of 100, 20, and 25 feet for the LDR1 principal building, so a lot's usable building envelope is constrained by both the setback lines and the 20% impervious ceiling simultaneously. An applicant proposing to exceed the impervious cap, whether through an oversized driveway or a pool deck, needs either to redesign the project or seek variance relief from the Zoning Hearing Board under Article XI.