How to Order & Install Replacement Windows
Switching out your old sash windows with new vinyl or wood replacement units is one of the most dramatic ways to change both the look and efficiency of your home. The process is deceptively easy---in fact, getting the right measurements to order the new window is the most complicated part (and the most crucial, since the windows have to be custom-fit). Unlike old windows, which were installed in pieces, modern units come fully self-contained and pre-hung, making it a simple matter of popping it into the opening. Does this Spark an idea?
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Things You'll Need
- Tape measure
- Pencil
- Hammer
- Flatbar
- Level
- Fiberglass insulation
- Razor knife
- Wood shims
- Screwgun
- Mounting screws (should come with your window unit)
- Window unit
- Caulk
Instructions
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With the old window still in place, measure the width of the opening by holding your tape measure against the furthest part of the window jamb, just behind the piece of interior stop-trim that holds in the sashes. Take the measurement at three different points along the sides (you'll have to lift the bottom sash to take a measurement on the lower half).
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Take the smallest of the three measurements. Subtract 1/4 inch from it. Write it down. This is your width reading for ordering your new window. Follow the same procedure to measure for the height, taking three measurements, then subtracting 1/4 inch from the smallest of them. Order your window with your adjusted height and width readings.
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3
When your new window unit arrives, measure it to ensure it is the proper dimensions.
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Remove the old window by gently prying off the vertical stop-trim with your hammer and prybar. Don't break it, as you'll need to re-install it. Pull the bottom sash straight out. Remove the vertical dividing strip that was behind the bottom sash, and pull the top sash out. Leave the exterior stop-trim in place.
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With your razor knife, cut a strip of insulation as wide as the new window unit and a little thinner. Set it on the window sill. Lift your window unit and set the bottom of it directly on the insulation. Push the rest of the unit into the opening, tucking more insulation in along the sides as you do. Let the window come to rest against the exterior stop-trim.
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Use shims to get the window straight and square in the opening, holding your level at various points on the window and tapping the shims in between the edges of the window unit and the jamb as needed. Secure the window by sinking mounting screws in through the sides of the unit into the jamb. (Generally, the kit will include three or four screws per side.)
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Re-install the stop trim to trap the window unit in the opening. Caulk between the unit and the trim.
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Tips & Warnings
Wear gloves when handling the fiberglass. Wear eye protection when removing the old window.
