What is impervious surface?
While I try to keep my blog posts interesting, there is no denying that some topics are drier than others. This one is a good example (though, when I think about it, “dry” is actually the matter at hand).
In the Philadelphia suburbs,we get a fair amount of rain. In order to ensure that adequate drainage is maintained (as well as keeping the area green and not too much of a concrete jungle), there are limits to the amount of impervious surface you can have on your property. Impervious surface is any kind of built structure, driveway, swimming pool, patio, deck–anything that doesn’t absorb water. Pretty much anything other than dirt.
How much is allowed?
Depending on the specific zoning, the maximum allowed is usually between 20 and 28%, though there are certain special circumstances. If you want to build a pool, add a garage or put on an addition, check with the township before bidding on a property. In addition to telling you the requirements/restrictions for the lot in question, they will almost always tell you that you need to have a survey done to pinpoint exactly how much impervious surface is currently in place.
Other zoning ordinances
Furthermore, there are other zoning requirements including setback minimums allowable types of fences. You may encoutner specific rules like not being permitted to convert a garage into living space. Other local regulations address the removal of trees (sometimes you must plant one if you take one down; in other places, you may not be permitted to take down more than a certain number). Storm water management is another possible complication. If you are doing any kind of regrading, there may be a maximum percent change permitted as well as restrictive requirements about managing the changed flow of water from those projects.
You also may not be permitted to run any kind of business (including an office client/patients come to) on a residentially-zoned parcel. Another “no-no” is the (popular in Colorado and other southwestern states) accessory dwelling unit (ADU). They are commonly known as granny flats. Here, unless the property is on multiple acres, you cannot have more than a single residence. There are plenty of rules and disallowed uses–be sure you check thoroughly before making assumptions about how you can use the property.
If you are relocating to the Philadelphia/Main Line area, please go to my relocation tab. If you’d like to read other blog entries related to relocation, please scroll down a couple of lines from here and click on RELOCATION (to the right of FILED UNDER). Thanks!