There are so many different options when it comes to building an addition, but the most important aspect when considering a new project is your township’s impervious surface regulations. Your project may or may not be permitted by the local township based on the ratio of building coverage to green or impervious surface area. To determine what your township’s regulations dictate, you can call your local township office.
In many cases, building upward or adding floors vertically is absolutely fine. But when you get into building outward you can run into problems.
Bucks County defines an IMPERVIOUS SURFACE as any surface which does not absorb rain; all buildings, parking areas, driveways, roads, sidewalks and any areas in concrete, asphalt, packed stone, pavers on sand or other equivalent surfaces. In addition, other areas determined by the Township Engineer to be impervious within the meaning of this definition shall also be classified as impervious. For purposes of this definition, the areas of a swimming pool or pond located inside the coping shall be classified as impervious.
NET BUILDABLE SITE AREA – Net build-able site area is calculated for the purpose of determining allowable impervious surface and land permitted to be developed. Net build-able site area equals total lot area contained in the subdivision or land development application:
(a) Minus ultimate rights-of-way of existing streets;
(b) Minus land which is not contiguous or which is separated from the site by a road or railroad;
(c) Minus land shown on previous subdivision or land development plans as reserved for open space or other uses which restrict it from development;
(d) Minus all land restricted by easements or covenants; and
(e) Minus land required to be left open for resource protection or to meet minimum open space requirements of this chapter.
Adding a second floor is fine but a whole addition may not be permitted due to the ratio of building coverage to green area or impervious surface.
We have found that different townships have different regulations and the best way to find out what the specific rules you have to observe are will be to check with your home township office.