This story shows you how to build a temporary support for the ceiling for use while installing a new window.
When framing for a window in a new location, it is usually easiest to cut an opening in the interior drywall that is quite a bit larger than the window opening. This will require you to patch the walls afterward, but installing framing -- especially the header -- inside a wall is difficult. If you have plaster walls, you may want to try the surgical method shown on the opposite page.
It is also usually easiest to leave the exterior sheathing and siding in place while you cut the studs and build the framing. This prevents having to replace siding. However if you will be replacing the siding anyway, you can cut a large opening in the exterior at the same time you cut the interior opening. If the window has brick molding or a flange, you will need to cut back the siding to accommodate it.
If you have a brick wall, hire a professional mason to cut an opening. When framing always work carefully to produce a structure that presents a smooth face for the drywall. Install adjoining pieces perfectly flush with each other.
A full day to remove interior drywall and frame for a window
Tape measure, stud finder, hammer, nail set, flat pry bar, drill with screwdriver bit, level, combination square, framing square, reciprocating saw, handsaw, stapler
Measuring, marking, cutting
Place drop cloths on the floor and seal the doorways to prevent dust infiltration. Place a fan in a nearby window and point it outward.
2x4s or 2x6s for framing, shims, 16d and 10d nails or 2- and 3-inch deck or wood screws, plywood, staples
You will need at least one new king stud (see the left side of the opening in the illustration below), which is the same length as the other existing studs. Cut two cripple studs; the sill will rest on their tops. (A jack stud will be fastened above so it and the cripple stud sandwich the sill.) Drive a fastener every 12 inches or so, in an alternating pattern.
Install a king-and-cripple stud combo by wedging the king stud between the top and bottom plates. If framing a cavity push the king-and-cripple stud halfway behind the drywall and drive angled 10d nails or 2-inch screws. (Fastening will probably move the studs over slightly, so start with the studs offset by 1/4 inch or so.)
Mark for the header. Hold a level atop the jack stud and mark across the studs to indicate the bottom of the header. Measure upward to mark where the top of the header will be. Make cutlines about 1/8 inch higher than the measurement. If there is a gap, fill it with shims. Make the bottom cuts (step 7) about 1/8 inch lower than the measurement.
If patching walls will be difficult (as when you have plaster walls), you may choose to slip the new framing in. Cut a section of the finished wall that is the correct size of the opening. Use a reciprocating saw to slice through the studs above and below, taking into account the widths of the header and sill.
To build the header, cut two pieces of 2x6 or 2x8 to the width of the opening plus 3 inches. Cut strips of 1/2-inch plywood as spacers. Lay the 2xs on top of each other to determine which direction (if any) they "crown," bend upward in the middle. See that their crowns face the same way. Position a spacer every 8 or 10 inches, lay the second 2x on top, and drive two or three 3-inch screws.