How To Install a Vinyl Replacement Window

Replacing wood-sash windows with vinyl windows is simpler than you may think.

Taking out inefficient windows and replacing them with new ones will give you a dramatic look at how much home improvement has changed over the years. Old wooden double-hung windows were built in pieces right into the window opening. New vinyl windows come pre-hung in a single unit, allowing you to slide the unit into the opening and secure the edges without having to worry about getting the sashes to work right.

Things You'll Need

• Tape measure
• Hammer
• Pry bar
• Replacement window
• Mounting screws (should come with the replacement window)
• Screw gun
• Shims
• Level
• Fiberglass insulation
• Caulk

Instructions

1. Order your new window before you remove the old one. Take three width measurements at three points in the window opening--top, middle and bottom. Measure from the widest point of the window jamb, just behind the vertical piece of stop-trim that holds the sashes in place. Take the smallest of your three measurements and subtract 1/4 inch from it. Write that down as your width measurement. Follow the same procedure to measure the height of the opening, subtracting 1/4 inch from the smallest of three measurements.

2. When the new window arrives, remove the old window. Carefully take off the vertical stop-trim pieces using your hammer and pry bar; don't break them, as you'll need them later. Pull the bottom sash straight out. If it's attached to window weights, cut the rope or chain and let the weights fall inside the walls. Remove the vertical divider strip and take out the top sash. Leave the exterior stop-trim in place. Examine the sides of the jamb to make sure there are no nail heads or other obstructions.

3. Lay a strip of fiberglass insulation on the windowsill. Set the bottom of the new window on the sill over the insulation. Push the top of the unit up and in slowly, tucking fiberglass insulation around the sides and top as you go. The exterior stop-trim will prevent the unit from falling through.

4. Use your hammer to tap shims between the sides of the window unit and the window jamb, using your level to determine when the window unit is level and plumb (straight up and down). Once it's right, use your screw gun to sink long mounting screws through the sides of the window into the jamb (two to four per side, depending on the unit). Reinstall the interior stop-trim to hold the window in place. Caulk all of the edges.

Tips & Warnings

• Wear eye protection when using your screw gun.