There are two main criteria:
First, there is the Minimum Average Lot Grade Requirement:
Per the Village’s flood hazard protection ordinance, the Average Lot Grade must be greater than the Minimum Average Lot Grade. That means that if you took the average lot grade, which is the average of the existing elevations taken at the intersection of the setback lines, it must be a greater value than the Minimum Average Lot Grade. The Minimum Average Lot Grade Equations is as follows:
Minimum Average Lot Grade: (627.3-2) - [(total required side yard permitted by Zoning – 12’) x 0.0833]
It is recommended that the prospective builder consult with a Professional Civil Engineer to investigate the logistics of constructing a new home with a basement on a lot.
Second, there are clay pad construction restrictions which may directly affect the size of the home, and are as follows:
- The lowest finished grade for the top of the clay pad must be at least to the FPE, and extend at least 10’ beyond the exterior face of the home’s foundation wall, around the entire perimeter of the home, before dropping to the BFE;
- The BFE must extend at least 20’ beyond the exterior face of the home’s foundation wall, around the entire perimeter of the home, before dropping below the BFE;
- The basement floor elevation can be no deeper than 5’ below the BFE;
- The elevation of the lowest opening in the basement wall (i.e. window wells, access ways…) must be at or above the FPE. This means that all window wells/access ways and the like, must be integrally constructed with the foundation wall, with no joints or seams;
There are additional criteria that must be met, but they are more material related.