A door can match the width and height of the opening and still be a poor fit if there is not enough room for the tracks, springs or opener. The complete interior garage space needs to be considered.
Opening
Confirm finished width and height rather than relying only on a nominal door size or an early construction drawing.
Sideroom
Check usable space beside both sides of the opening for the selected vertical tracks, brackets and counterbalance configuration.
Headroom
Measure from the top of the opening to the first ceiling or structural obstruction and match the track system to the available space.
Backroom
Confirm enough unobstructed depth for horizontal track travel and, where used, the automatic opener rail.
Obstructions
Note beams, pipes, ductwork, lighting, storage racks, ceiling equipment or another object that could conflict with the door trajectory.
Framing
If the surrounding structure or opening needs to change, separate that building work from the garage-door specification and confirm any applicable project requirements before installation.