Residential Addition/Expansion Requirements

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Are you thinking about expanding your home? Here are some helpful hints to determine whether your proposed expansion will comply with the Lower Merion Zoning Code.

  1. The first step is to determine the "Zoning Classification" of your property. Use the Zoning Classification Search Form or get the definitive answer from the Township's zoning map, located in the Building & Planning Department.
  2. Once you determine the zoning classification, check the zoning code to determine the setback requirements (Zoning Setback Requirements) from your property line, and the maximum building and impervious coverage permitted on your property. This will establish your building envelope. The building envelope is the area in which you are permitted to build. A setback chart is attached below.
  3. After you determine that you can comply with the setback requirements, you must calculate the amount of "impervious surface" (Impervious Surface Calculation Guide) that covers your lot. Impervious surface is "any material placed on or above the earth which substantially reduces or prevents the natural percolation of water." Examples include but are not limited to: structures, including eaves, roofs and roof overhangs; parking areas, driveways, sidewalks, patios and decks, sport courts, and pools (anything other than grass).
  4. You must locate any on-site sewer system, sewer/stormwater easements, and flood plain area if applicable. No portion of a building is permitted over any of these areas.
  5. Preliminary drawings can be submitted to the Building Regulations Division of the Building & Planning Department to determine if the proposed expansion meets the required setbacks and impervious cover limits.
  6. Once established that you comply with the requirements of the zoning code, you can proceed to have architectural plans prepared. If the improvements include structural alterations, the plans must be sealed by an Architect or Professional Engineer licensed in the Commonwealth of Pennsylvania.
  7. Two (2) sets of plans are required. If you are creating your own drawings they must be to scale and show sufficient details of the proposed improvements. (A plan submission checklist can be obtained from the Building & Planning Department.)

A survey is not always required as long as you can demonstrate that the expansion will comply with the setback requirements. The Building Regulations Division reserves the right to require a survey.

Expansions (buildings, pools, driveways, etc.) disturbing over 1,500 square feet of land area may require an engineered plan and an Application for Runoff & Erosion Control Permit from the Planning Division of the Building & Planning Department. This requires a detailed set of engineered plans and typically requires the installation of a stormwater management system to reduce the rate of runoff onto adjacent properties.

Separate permits are required for Building, Electrical, Plumbing, Heating & Air Conditioning and alarm installations. If a new curb cut is proposed, a permit is required from the Public Works Department. The permit fees are based on the type and cost of the work.

We recommend that you avoid delays during the busiest season (spring and fall) by obtaining all permits in the summer or winter. You have six months from the date the permit is issued to begin work.

Zoning and Setback Requirements
Single-Family Dwelling

Chart of Zoning Requirements