How to Install Wood Replacement Windows
- 1). Measure the width and height of the window opening, with the old window still in it. Measure from the furthest outward spots on each side, moving the window sashes up or down as needed to get at the frame. Take measurements in three different spots for both the width and height. If there's any variation, select the smallest number for both the width and height. Add 1/2 inch to the width and height numbers, and order the window at those adjusted dimensions. (So if the three width measurements are 30, 30 1/8 and 30 3/8, your adjusted width measurement would be 30 1/2.)
- 2). Remove the old window only after the new window arrives. Take out the old window by using your hammer and pry bar to pry off the trim that borders the edges of the window opening and face inside the room. Don't break it as you remove it. Set it aside.
- 3). Remove the bottom window sash by pulling it straight out into the room. Pry out the second strip of trim holding in the upper sash, and remove the sash. Leave in place the perimeter of exterior "stop trim" bordering the opening on the other side.
- 4). Cut enough strips of fiberglass insulation to fit around the whole window opening, using your utility knife. Set one strip on the window sill. Set the bottom of the new window unit on top of the insulation.
- 5). Push the top of the window into the opening. Slip more insulation strips in around the sides as you push in the window. Push until it butts up against the external "stop trim" on the outside of the opening.
- 6). Put a level on the window and shim it at the sides and bottom until it's level. Secure the window by diving in mounting screws through the holes in the sides, using your screw gun.
- 7). Put the interior trim (that you removed earlier) back in place around the window, using your trim nailer. The trim should trap the new window unit in place. Caulk the unit's perimeter, inside and out.