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# Creating Objects Above/Below Grade
In most places around the world, the Building Coverage Area is defined as the building's footprint on site, with some slight differences by conditions. In our explorations, we calculate the Building Coverage Area by the projected area of any geometry that is above ground.
## Any object that is visible above ground is used for Coverage Area Calculations
We consider elevation 0.0 to be ground level. Usually only objects on levels above ground are used for calculating the coverage area.
However, even for objects placed on levels below ground, if their geometry is visible above ground, we use them in our coverage area calculations as well.
In the following two images, we have a below ground space, colored in purple, with its roof partially above ground.
Because its roof is above ground, in our explorations it will be used for coverage area calculations.