One of the restrictions or controls specified by zoning district is Lot Coverage. This tells how much the footprint of a building could cover the lot.  

Usually, the zoning gives a percentage of the lot area for any structure. The way you calculate it is by multiplying the size of the lot with the percentage.

For instance, if your lot is 3,000 sqft and the Lot Coverage allows for 50%, that means all the structures on the lot that touch the ground may not be larger then 1,500 sqft.

CityStructure report expands the building footprint to the maximum lot coverage allowed by the zoning district.