There are three types of openings you will need to frame into the walls.
- Windows
- Man or pass doors
- Overhead doors
Rough opening size, see Figures 7a, b, c
Prehung doors and windows have a specified rough opening size. This is the size of the opening in the frame before you install the door or window and any trim. You can get this number from the manufacturer in the paperwork supplied with the door/window. These are the measurements you will build your frame to.
All other dimensions are dependent on the rough opening size.
Build the frames before you build the wall it goes into. This way you will have it for reference while marking the wall lay out. If you get confused you can actually lay it in place to visualize it’s proper placement.
Header length
The header is the piece of wood that goes over the top of the opening and takes the weight of the roof and wall above.
The cut length for the header is the rough opening width plus the width of the jack studs. For an opening up to about 6 ft a single jack stud on either side is sufficient.
For larger openings you might want to use 2 or even 3 jack studs on either side.
Header size
The header size for a load bearing wall is different than the header size for a non load bearing wall because there is no weight on a non load bearing wall.
The gable end wall has no weight because the truss is carrying it. But the sidewalls are load bearing because the trusses rest on the wall and transfer the weight to it.
So the size of the header depends on the opening width and if it’s a load bearing or non load bearing wall. It’s ultimately dictated by your local building code.
- For a rough opening between 2 studs that doesn’t break a stud, a flat 2×4 header is sufficient.
- For rough openings up to 36 inches a sandwiched 2×4 header is sufficient.
- For rough openings up to about 60 inches a sandwiched 2×6 header is sufficient.
- For rough openings of up to 16 ft on a non load bearing wall a sandwiched 2×10 is sufficient.
- For rough openings of 16 ft on a load bearing wall you will probably need an engineered header with the associated paperwork to satisfy the building codes department.
Jack studs
The jack stud transfers the weight from the header to the foundation.
For door openings the jack stud length is the rough opening height less the bottom plate thickness of 1 1/2 inchs, if the bottom of the door is flush with the finished floor height.
For windows the jack stud length is the rough opening height.
Prehung windows, see Figure 7a
Rough opening height (“g”) for a window is from the bottom of the header to the top of the ledger.
The sandwiched window header (“h”) is (3 inches) longer than the rough opening width (“f”).
Note the cripple studs above and the short studs below the window fall on the 16 inch centers so you have something to nail the siding to. Cut both of these to fit.
As a general rule for aesthetic purposes the top of the windows should be at the same height as the top of the doors (dimension “a”). But feel free to set the height at what ever works best for your situation.
Prehung doors, see Figure 7b
Rough opening height (“c”) for a door is from the bottom of the header to the top of the floor. Cut the bottom plate out after the wall is raised and bolted in place.
The sandwiched door header (“d”) is (3 inches) longer than the rough opening width (“b”).
The jack stud (“e”) is 1 1/2 inches shorter than the rough opening height (“c”).
Note the cripple studs above the door fall on the 16 inch centers so you have something to nail the siding to. Cut them to fit.
Overhead doors, see figure 7c
This is the typical rough framing for a 7ftx16ft overhead door on a standard height outside wall, 24ft long.
- The rough opening height (“j”).
- The jack stud (“k”).
- The rough opening width (“m”).
- The header length (“n”).
Minimum spacing, see Figure 7d
The minimum spacing from the corner to an opening, or between 2 openings is 32 inches. Figure 7d shows the framing you would use to put 2 overhead doors on the same wall. It uses 3 jack studs and 2 king studs on each end of the header.
This is a typical inside wall of standard height where the first stud is 3 1/2 inches inside the corner using 2×4 wall studs. For 2×6 framing the first stud would be 5 1/2 inches inside the corner.
The only difference for an outside wall would be the location of the first corner stud.
Notice that the cripple studs above the headers continue at 16 inches on center.
This wall could be for two 16ft overhead doors or for an 8ft and a 16ft door. Or for a pass door and a window, or an overhead door and a pass door etc.