The rough opening should be the same size as the door. Common garage door widths include 8′, 9′, 10′ and 16′. Common heights include 7′ and 8′. Measure headroom as the distance between the top of the door and the ceiling (or first obstruction, e.g., light fixture).

Most standard automatic openers require at least 12 inches of overhead clearance, some taking 18 inches. This includes about 12 inches for the door and torsion springs and three inches for the garage door opener.

Yes, an 8-foot garage door is wide enough for a single-car garage. Standard, single-car garage door widths start at 8′ for single-car garages and increase in 2″ increments to 20′ wide. Double car garage doors typically start at 12′ wide and increase in 24″ increments to 18′ wide.

Normal Thickness: Typically, garage doors are between half an inch to 1 inch thick. This is thick enough to provide some separation between you and the external environment. However, in the end, it's only a small sheet of material. Thus, it tends to be susceptible to dents.