How to Add a Window to My Unfinished Basement

Mark the outside siding with a permanent marking pen for the window cutout. Make sure there are no plumbing pipes or electrical lines in the section of wall where the window will be installed. Visit your local home improvement center to see what stock size windows it carries. Making your cutout a stock size will make it easier to buy a window and replace it later if need be. If you have a concrete or block wall, you may need to get a professional contractor involved.

Drill 1/4-inch pilot holes in the corners of the window cutout. Cut the opening using the sawzall. Frame in the window opening using 2-by-4 studs. Install a window header, which is usually 4-by-4 post material. Along both the left and right side of the window, install two studs per side. These are known as "king" studs and are used for support of the header and window. Nail these studs in place, running them up to the header and down to the stud plate at the bottom of the existing wall.

Wrap the sticky flashing tape around the window hole edges. Fold in the sides and cut at the corners to allow the foldback. This weatherstripping material will help prevent any leaks.

Place shims on the bottom ledge of the window area and level them. Use small nails to hold them in place. Place the window into the opening and level it. Use a plumb square to make sure the window is plumb, too. Drill a few drywall screws into place to hold the window in. Level and place screws as you work your way around the frame.

Spray window and door foam insulation into any gaps and let dry. It will slightly expand to fill all the gaps and spaces. Install your window trim.