How to Install Egress Basement Windows

Determine the location and size for your egress window. Egress windows must provide at least 5.7 square feet of opening space with measurements of at least 20 inches wide and 24 inches high. The window cannot be more than 44 inches from the floor. You can make the egress window bigger, but you must meet these minimum requirements to comply with building codes. A smaller window may save you from having to install a header beam to provide extra support.

Dig a hole outside your home near the location where you are planning to install your window. The hole should be at least 6 inches deeper than the window's bottom and about 48 inches square.

Tape off the inside wall where you will install your egress window. Add 3 1/2 inches to the size of your window and use masking tape to mark the measurement.

Place a 12-inch masonry drill bit in your hammer drill. Find the center in the bottom line of your masking tape. Drill a pilot hole.

Use a 14-inch concrete saw with a diamond blade to cut around the perimeter of the area for your window opening. Cut a 1/2-inch-deep cut through your basement's concrete block, starting at the bottom corner. Repeat the cut to get a depth of 1 inch with a second pass of the concrete saw. Hire a professional if you have a poured concrete wall, rather than concrete blocks.

Make the same cut in the exterior portion of the wall. Use a concrete saw to cut the concrete blocks.

Continue to saw around the area for your opening until you have formed a rectangular shape with the cut. Use a hammer and knock out the concrete blocks between your cut lines.

Build a pressure-treated box that will fit inside the hole you created. Use a 2-by-10-foot pressure-treated board and cut it to equal the thickness of the hole. Apply adhesive to the sides of the board that will be flush against concrete blocks. Fit the box inside the hole. Drill concrete screws into the box to attach it to the opening.

Fold the metallic edges of the window out. Apply caulk with a caulking gun around the inside edge of the pressure-treated box. Place the window inside the box, making sure that it is level. Hammer mounting screws into the metallic sides of the window into the box.

Add mortar to the concrete blocks surrounding the box with a spackle knife. This will fill in any holes that were created when you made the opening.

Hammer the outside trim to the top and sides of the window. Add caulk with a caulking gun around the trim to fill any gaps.