In new construction most doors are hung after the floors are



installed. This allows flooring contractors (tile, hardwood,

vinyl, laminate) to lay their flooring products without

making tricky cuts around door jambs. It also makes for a

neat and clean door installation. Exceptions to this are

carpeted floors. Doors are hung before the carpeting is

laid. When doors are hung in carpeted areas, its a good idea

to shim them up 1/2", putting a shim under each jamb leg.

This eliminates the need to cut the doors down after the

carpet is installed.

For a 6' 8" high door (80 inches) I like to frame my rough

opening heighth at 82 3/4". This allows room for all the

situations mentioned above. If your header material is a

double 2x12, holding it to the top plate will give you that

heighth.

Rough openings for door widths are pretty much standard. The

rough opening width is 2 inches wider than the door itself.

this allows room for the door jambs which are usually 3/4"

thick. This gives you approximately 1/2" of play and shim

room when installing a prehung door. For a 36" door (3' 0")

the rough openig width would be 38". Here are the most

common door sizes and their rough openings.

Door Size Rough Opening Size

2' 0" x 6'8" -26" x 82 3/4"

2' 2" x 6'8" -28" x 82 3/4"

2' 4" x 6'8" -30" x 82 3/4"

2' 6" x 6'8" -32" x 82 3/4"

2' 8" x 6'8" -34" x 82 3/4"

2' 10"x 6'8" -36" x 82 3/4"

3' 0" x 6'8" -38" x 82 3/4"

To figure the rough opening for double doors or french

doors, take the door size times 2 and add 2". The most

common sizes for exterior doors are the 2'8" and the 3'0"

doors. The 2'8" is usually used for the back door and the

access door from the garage. That size door for exterior use

is being used less these days because of the size of

appliances and furniture. Exterior doors with sidelights and

sliding patio doors rough openings vary from manufacturer to

manufacturer. These should be verified and gotten from the

supplier.

Getting the rough openings right the first time keeps the

sawzall in its carrying case and having to change the

opening after the walls are drywalled and painted.

To learn more about installing doors, check the archives of

this blog or go to www.sawkerfs.com

Mike Merisko (c) 2006

www.sawkerfs.com