Replacing a window can be done by anyone with common carpentry tools
and basic woodworking skills. Windows are readily available in standard
sizes, or they can be ordered from a manufacturer or lumberyard in
special sizes to fit your rough openings.
If the opening is square, take final measurements between the left and right window jambs at the top, middle, and bottom. The shortest of these three measurements is the window width. Next, measure the distance between the head jamb and windowsill at the left side, middle, and right side of the window. The shortest of these three measurements is the window height.
•Remove the old window To begin removing the window, work slowly and carefully to avoid damaging the existing molding, trim pieces and window casing. If the trim pieces have several decades of paint on them, score or cut around the trim with a utility knife to break the paint and calking seal. Scoring the seams first will help reduce the chance of splitting the molding during removal. Use a 4 inch wide putty knife and carefully loosen the molding surrounding the window. If it is stubborn, use a thin pry bar, sometimes called a cat’s claw to remove the trim.
Remove the old window. If you are only replacing the window sashes in a double hung window, leave the window frame in place for now.
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If you are replacing the entire window, remove the inside stops on the left and right sides by prying them loose with a putty knife or pry bar. Next, remove the jamb liners on both sides by raising the lower sash about 6 inches and pry the liner loose. Lower the top sash and do the same thing. Then, remove the old sashes and jamb liners as one unit.
Square up the opening with wood shims if necessary.
• Install the new window jamb Now is the time to install the new metal liner brackets that were supplied with your window sash kit. Mark a level guideline inside each vertical jamb, and install a bracket every 4 to 5 inches along the sides of the jamb. Take care to keep these brackets level. Attach the new jamb liners to the liner brackets.
Install the new sashes. The upper sash goes into the track closest to the exterior of the house. The lower sash fits into the track closest to the interior side. Make certain both sashes move smoothly.
Install the new head stop and set the nails just below the surface with a countersink or center punch. Reattach the left and right inside stops. Set the nails.
If you are upgrading to an aluminum framed replacement window, the installation is different. Cut away the exterior siding around the window. Beginning at the bottom of the opening, apply window wrap to the exterior window opening and work your way up. Lift the window into position and screw one corner of the replacement window into place. Make sure you are anchoring it to solid wood such as a stud or header. Check the plumb and square of the window by measuring the diagonals again. Once square, nail or screw the rest of the window frame in place. Add a second layer of window wrap around the fins of the window frame.
Insulate the new window by putting expanding foam sealant in the gap between the casing and the new window. Cover the edges of the new window with painter’s tape to protect the frame surface. Excess foam can be scraped off when dry. Remove the tape, and calk. Replace the siding and exterior trim as needed, calk and paint.
• Replace the trim The interior trim molding can be reattached now. Remove the old nails by pulling them through the backside of the molding with a pair of pliers. This helps prevent surface damage. Nail the trim molding in place and counter sink the nails.
• Calk & paint With the trim installed; putty the nail holes, sand and prime. Then apply the finish coat of paint.
• Tools needed
- Tape measure
- Utility knife
- Putty knife
- Thin pry bar or cat’s claw
- Pliers
- Hammer
- Level
- Sash replacement window
- Wood shims (if needed)
- Nails
- Counter sink or center punch
- Caulking gun
- Caulk
- Wood putty
- Paintbrush
- Paint