One of the most confusing aspects of homebuilding can be the rough opening for an overhead garage door. It is one of the most frequent questions I am asked.

The rough opening for a garage door, simply put, is the actual size of the door itself. For example, if the garage door is a 7'0" x 16'0", then that is the size the rough opening should be framed to. This is also what the opening in the foundation should be. The studs and cripples will then stop right at the edge of the foundation.

The foundation usually drops 8" to allow the concrete floor to be poured over the top of it. This has to be accounted for when figuring the length of the cripples to get the right height of the overhead door header. Normally the floor is poured 3" below the top of the foundation wall. If the overhead door is 7' then 4 and 1/2" is subtracted from that height. This is the 3" drop and 1 1/2" for the bottom plate. Your total cripple length would be 6' 7 1/2".

Once the floor is poured, the door jambs can be installed. The width of these jamb pieces vary with the size of the wall and what the wall is finished with (brick, siding, dryvit, etc). The header piece is installed first, then the two side pieces. These go from the header to the finished concrete floor. Once the jambs are in the door can be installed. With the door installed the door stops are then put on either with or without weatherstripping.

If you know the door size of your overhead door, you know the rough opening. From there its determining where to start and stop your framing.

(c) Mike Merisko www.sawkerfs.com