Parking is one of the first things a site plan has to resolve, because the number of spaces a use requires, multiplied by the area each space consumes, often determines whether a building fits on a parcel at all.
Minimum counts come from the local zoning ordinance and are tied to the use — spaces per thousand square feet of retail, per dwelling unit, per seat, per bed. Requirements vary meaningfully between Chattanooga, Hamilton County, and the surrounding municipalities, so the applicable ordinance is checked at concept stage rather than assumed.
A standard stall is commonly nine feet wide by eighteen to twenty feet deep, with drive aisle width set by the parking angle: roughly 24 feet for 90-degree two-way aisles, narrower for angled one-way layouts. Compact stalls, where permitted, are limited to a share of the total count.
Accessible parking is set by total lot size under a fixed schedule — one accessible space for the first 25 total, two up to 50, and so on — with at least one in every six being van-accessible. Standard accessible stalls are eight feet wide with a five-foot access aisle; van-accessible stalls need an eight-foot aisle, or a wider stall with the standard aisle. Neither the space nor the aisle may slope more than two percent in any direction.
Getting the count and the geometry right early avoids the far more painful exercise of shrinking a building late.