How to Frame Exterior Openings for Windows

Add five inches to the width of the window to determine the rough opening width.

Locate the the center of the space where the window will be installed. Divide the rough opening width in half and mark this distance from the center on both sides of the center to lay out the edges of the window opening. Use a speed square to draw a line across the bottom plate at the marks. Place an X beside these lines on the outside of the window opening.

Measure the distance from the bottom plate to the top plate and cut two studs to this length.The bottom plate is the 2 by 4 that lies flat on the floor and the top plate is the 2 by 4 that marks the top of the wall and is parallel to the bottom plate.

Install one stud on either side of the window opening. Align the edges of the stud with the lines drawn, making sure to put the stud on the same side of the line as the X. Nail three nails at an angle through the stud into the bottom plate. These studs are known as king studs.

Plumb each stud using a 4 foot level. When the bubble is in the middle of the two black lines on the vial the stud is plumb, or level vertically. Once the studs are plumb, nail them into the top plate using the same angled nailing technique, known as toe nailing, as on the bottom.

Determine the top of the window opening by adding the actual height of the window to the desired height of the bottom of the window. Measure from the floor and not the bottom plate and mark both studs at this height. Measure the distance between these marks and the bottom plate and cut two studs to this length.

Install these studs, called jack studs, next to the king studs. Make sure these jack studs face each other. Toe nail them into the bottom plate and nail them to the king studs.

Measure the distance between the two king studs just above the tops of the jack studs. Create a header by cutting two 2 by 10s to this length. Also cut a piece of 1/2-inch plywood to the same length and height as the 2 by 10s. Place it between the 2 by 10s and nail the header together. Make sure to nail from each side of the header.

Place the header on top of the jack studs and fasten it in place by nailing through the king studs into the ends of the header. If this is not possible due to space constraints, toe nail through the face of the header into the king studs.

Install cripple studs between the top of the header and the top plate by measuring the distance and cutting them to length. Nail them in place following the same 16-inch on center spacing that the rest of the wall uses. Short studs, usually placed between a plate and a header or a plate and a sill are referred to as cripple studs.

Measure from the bottom of the header to mark the top of the window sill on the jack studs. The distance should be the height of the window plus two inches.

Measure the distance between the jack studs where the sill will go and cut a 2 by 4 to this length. Nail the sill in place.

Install the cripple studs under the sill plate in the same manner as above the header.