How to Rebuild Double-Hung Windows

Cut away any old paint or stain with a utility knife.

Cut the balance cords on the bottom sash, using a utility knife. Lift out the sash. The weights can drop down inside. Balance cords are small ropes that lift the weight system up and down inside the window frame. These weights then lift or close each sash. The balance cords work on a pulley system.

Pull out the parting stops with a pair of pliers. Parting stops are small pieces of vertical trim on both sides of the window that hide the mechanical parts such as the pulley system inside the window frame. Repeat the process for the top sash.

Remove the balance cord pulley system by unscrewing it with a screwdriver. If this can't be done, drive them into the jamb with a hammer.

Install sill wrap along the bottom edge of the window sill. Sill wrap is a sticky back material used to waterproof windows.

Measure the width and height of the opening you now have. Use these measurements to order the new pocket window.

Place the new pocket window within the opening. Hold it in place with a helper and place a couple shims below the window. Level the new window as you go.

Install stainless-steel screws in the side of the frame, two per side, to hold your window in place while you make adjustments. Use a cordless drill and screw bit.

Install three or four stainless-steel screws on all sides of the window frame. Small windows may need only two screws. Operate the window a few times as you install more screws and shims to make certain it operates smoothly.

Push backer rod insulation into the gaps between the window frame and wall studs.

Spray non-expanding foam in the gap to fill up smaller spaces. Measure for trim installation.

Place a chop saw on a table that is about 6 to 8 feet long. Cut your new trim to size. Nail the trim in place, using 8-penny nails and a hammer. Install a bead of silicone around the new trim. Let dry for several hours.