Jamb

A jamb is the vertical structural member that forms the side of a garage door opening. Each opening has a left jamb and a right jamb, running from the floor to the header above. They define the width of the opening and provide the mounting surface for nearly all the hardware that holds the door system in place.

The vertical track bolts to a jamb angle or directly to a wood nailer attached to the jamb face. The flag bracket that connects the vertical track to the horizontal track is lag-bolted into the jamb at the top corner of the opening. The end bearing plate for the torsion spring shaft is also mounted to the wall near the jamb.

Jamb material varies by construction type. In a wood-frame garage, the jamb is typically a doubled 2x6 or 2x8 stud with a flat 2x4 or 2x6 nailer board face-nailed to it, creating a flat surface for track attachment. In a masonry or concrete block garage, anchor bolts are set into the block and the track hardware bolts to a steel angle or plate anchored to the masonry.

The weatherstrip jamb seal compresses against the jamb face when the door is in the closed position, blocking air and light from entering on each side.

The opening size is measured between the two jambs. A correct measurement taken from the actual jamb faces determines the door width. Obstruction within about 3-4 inches of the jamb can interfere with the track and hardware, so installers check side room before ordering.