Measuring & Site Assessment
Opening dimensions, headroom, backroom, sideroom requirements, and site conditions that determine hardware selection.
- Measure opening width and height to determine door size
- Calculate headroom, backroom, and sideroom requirements
- Assess site conditions including level, plumb, and square
- Select track configurations based on available clearances
Leçon 1
Opening Width, Height & Critical Measurements
Taking Accurate Measurements
Every garage door installation begins with precise measurements. The opening width is measured at the widest point between the finished jambs, while the opening height is measured from the finished floor to the underside of the header. These two measurements determine the door size you will order.
For residential installations, standard opening widths are 8 ft, 9 ft, 10 ft, 12 ft, 16 ft, and 18 ft. Standard heights are 7 ft and 8 ft. Commercial openings vary widely and are always custom-measured.
Always measure width at three points - top, middle, and bottom of the opening. Measure height at three points - left, center, and right. Use the smallest measurement for ordering. If the opening is out of square by more than 1/2 inch, note this for shimming during installation.
Rough opening dimensions include the structural opening before finished jambs. The finished opening is the dimension after jamb material is installed. Always confirm which measurement the manufacturer requires for ordering.
Always measure opening width and height at three points each and use the smallest measurement for ordering - this ensures the door fits within the available space.