Garage Door Rough Openings

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