To build a frame for a new window, first remove the existing window, and then cut the space to accommodate the new window, install the frame boards, install the new window and perform finishing work. Consult a professional with any questions regarding the installation process.
To make the frame for a new window:
- Remove the existing window
- Create the new sill
- Create the new frame
- Install the new window
- Perform finish work
Remove the existing window by first removing the interior and exterior trim and sill. Cut away the existing caulking and carefully pull the old window out of the frame.
Measure the size of the new window and cut the existing space to fit the new window plus an extra 3/4 inches on each side. The extra space allows enough room to adjust the window until it is level.
Nail down a new 2-inch-by-2-inch board against the old sill to create a new interior window sill.
Use 2-inch-by-4-inch boards along the top, bottom and sides of the opening to create the frame for the window.
Place the new window into the framed opening. Nail it into place with just one or two nails, and use shims to adjust the placement of the window until it is level. Screw the window into place.
Fill the gaps around the frame with caulk or expanding foam. Install new trim around the window and caulk and paint to finish the job.