Ceiling Clearance
The vertical distance from the floor of the hitting area to the lowest point on the ceiling, accounting for beams, ducts, lights, and fixtures. Different from raw ceiling height, which often overstates usable space.
For most amateur golfers, 9 feet of clearance is the practical minimum for a comfortable full driver swing. 8'6" is workable for shorter players or iron-only practice. 10 feet+ is generous and accommodates virtually anyone.
Measure to the lowest obstruction, not to the drywall — a ceiling fan or HVAC vent at 8'4" defines your clearance, not the 9'2" plaster above it.