Where the requirement comes from

Two things drive it: overhead bar travel and standing height on the carriage. The push-through bar on a tower must rise fully overhead, and a client standing on a carriage is already 12–16 in off the floor before they raise their arms.

For a 6 ft user standing on a 14 in carriage with arms overhead, you are at roughly 8 ft 2 in. That is the number that catches people out, and it applies to plain reformers too if you teach standing work.

Minimum ceiling heights by apparatus and use
SetupMinimumComfortable
Reformer, supine and seated onlyNo requirement7 ft
Reformer, standing work7 ft 6 in8 ft 6 in
Reformer with tower7 ft 6 in8 ft
Jumpboard8 ft9 ft
Full Cadillac7 ft 6 in8 ft

Basements and converted lofts

These are where the question usually arises, and the answer is usually workable. A 7 ft 6 in basement handles a plain reformer and a tower for average-height users, and simply rules out jumpboard work.

Watch for ductwork and beams. A room with 8 ft clearance and a 6 ft 8 in duct running across the middle effectively has a 6 ft 8 in ceiling wherever the machine needs to go.