How to Frame for Window Installation

Cut the king studs, which are studs running from the floor to the ceiling to provide support on either side of the window. If the window fits between two existing studs, you can use those, but often you will need to install the king studs for proper spacing to hold the window frame. Cut the studs from the same size of lumber as the existing studs, normally 2-by-4 or 2-by-6 lumber, so it fits vertically between the top and bottom frame of the wall. Nail the king studs in place.

Cut the header board from a piece of lumber based on local building codes, usually ranging from 2-by-6 to 2-by-12 depending on the size of the opening. Cut two pieces of the lumber so that it spans horizontally between the two king studs.

Sandwich the two header boards with half-inch plywood spacers in between so the header is the same thickness as the studs. Nail the header pieces together. Nail the header in place so the bottom edge of the header is at the top of the window opening.

Cut trimmer pieces, which are studs that go from the bottom edge of the header to the floor as a support system for the header. Cut the trimmers from the same size lumber as the studs. Nail the trimmers so they are against the king studs and under the header.

Cut pieces of the stud lumber to fit from the ceiling down to the top of the header. Nail these cripple studs in place using the same spacing as the rest of the studs on the wall.

Cut a sill board that establishes the bottom edge of the window frame. Nail it horizontally between the two trimmer pieces.

Cut additional cripple studs that span from the bottom edge of the sill board to the floor. Nail the cripple studs in place with the same spacing as the upper cripple studs above the header.