To find the dimensions of your garage door opening, measure the length and breadth of the opening using a measuring tape. Also, measure the gap between the garage opening and the roof of the garage, and the space between the garage's nearest wall and the sides of the garage door.
When measuring the length of your garage door opening, measure from the top to the bottom. Allow the measuring tape to fall to the ground to obtain accurate measurements. Use a stepladder to access the top portion of the opening.
To measure the width of the opening, measure from one side to the other at the top and bottom of the opening. If the top and bottom width dimensions differ, it indicates that the door frame is warped or slanted. Correct this difference before attaching a door.
Measuring the gap between the garage roof and opening helps to know how much additional space is available in the ceiling of the garage. This space determines what size the door's track components should be.
The space between the sides of the garage door and the nearest wall indicates the amount of side space available. This gap indicates how much space is available to house the tracks or motor of a garage door.