How to Fill in a Window With Wall Board

Measure the height of the window you want to cover with wall board using a tape measure.

Measure and mark two pieces of 2-inch by 4-inch lumber to fit the window's height dimensions. Put on goggles and cut both lumber pieces to fit.

Insert the 2-inch by 4-inch lumber pieces into the interior sides of the window and fasten to the studs supporting the window frame with a screw gun and screws. A frame must surround the window for installation, so you won't need a stud finder.

Stuff roll-up insulation into the window between the lumber pieces. Cut the insulation to fit with a utility knife. This will help to insulate the space and keep the wall board free of moisture seeping in from outside.

Measure and mark the wall board, then use a utility knife to score both sides of the wall board. Snap the excess off at the score lines by hand.

Insert the wall board into the window against the lumber pieces. Drive drywall screws into the lumber pieces with a screw gun to hold the wall board in place.

Tape around the edges of the window/wall board joints with drywall tape then spread joint compound over the entire area with a putty knife. Let the joint compound dry overnight then sand the area, prime and paint it to match the interior wall.