DIY Double Hung Window Repair

Use the procedure on this page to repair broken sash cords on double hung windows. We use cotton sash cord for this repair but a chain may be used in place of cord if desired. The picture below illustrates the anatomy of a double hung (two sash) window and the pulley/weight system for raising and lowering the sashes.

To repair a broken sash cord on a window like this the counter weight inside the window casing must be reattached to the window sash. This would be a simple task if not for the need to open the casing to get to the cast iron weight inside. Fortunately most antique, double hung windows have an access panel cut into the lower sash channel for this very purpose.

Below is a list of tools and materials you will need for this repair.

• Cotton sash cord 3|8 inch in diameter
• Large Chisel (a 3½ inches painters chisel is ideal for this)
• A wire hanger with a hook in the end or similar device for pulling cord thru the wall

Use the diagram below to identify the parts of the window casing.

Start the repair by removing the inside stop bead on one side of the window casing. Use a broad chisel and drive it with the flat against the side jamb at regular intevals to pry the nails free. Set the stop bead aside. Pull the lower sash from the casing tilting it out.

If both cords are broken remove the sash and set it aside while you string the counter weights. If only one cord is broken pull the sash free from the casing and let the good counter weight hold it off to the side while you work.

Remove the access panel. If the panel is held in by the parting strip use the chisel to pry it from its groove. Starting at the sill, drive the chisel with the flat against the strip. Pry the strip up digging into it slightly with the chisel to get a grip. Pry the parting strip free as far up the casing as needed to remove the access panel.

If there are nails or screws holding the panel in place, remove them. Opposing rabbets will usually be cut in the panel, one on the face and one on the back. Pull the panel free from the end with the rabbet on the back. You'll have to try lifting the ends to discover which is the right one.

Reach into the window casing and pull the loose counter weight and broken cord out. Untie the old broken cord, paying attention to how it is tied. You should use the same technique to tie the new cord. If you have trouble duplicating the knot just use a double knot that you are sure won't come loose.

Use a piece of cord long enough to reach from the sill of the window to top and down again. Fish the cord thru the top of the pulley opening. Push cord into the cavity rolling it in the pulley wheel to keep it going straight.

Use a wire hanger or similar device to reach thru the access hole and try to snag the cord. Keep pushing cord in letting it bunch up until you can hook. Pull the end down until it is accessable thru the hole. Pull some excess cord thru the hole making sure not to pull the other end into the cavity above. Tie the end of the cord to the counter weight.

Set the weight back into the casing and pull the cord tight from the pulley end. Suspend the weight to 4 or 5 inches above the sill level. Measure down the cord from the pulley the length of the groove in the side of the sash. Add about 5 inches to this measurement and cut the cord. Don't let the end fly up and into the pulley hole. Tie a tight double knot in the end. One tight enough to fit in the sash hole. Insert a long nail or screw thru the knot to keep the cord from being pulled thru the pulley hole when you let it go.

Remove the old broken cord from the window sash. A nail is driven thru the cord knot and into the sash. Pull the nail free with needlenose pliers and save it. While holding the sash in the casing and tilting out to access the side, pull the cord down from the pulley. Remove the long nail and insert the nail you removed from the sash. Push the knot and cord down flush with the side of the sash. Drive the nail thru the knot and into the sash using the same hole it came from. Use a phillips screwdriver or a nail set to sink the nail until it's tight. Slip the sash back into place and gently raise it into the open position.

Install the access panel and refasten it. Tap the parting strip back into its groove and pull the window sash down. Install the stop bead, lining the nails up to go back into their original holes. Gently drive the nails home. Test the window for glide, if it binds, use the chisel to nudge the stop bead out a little until it moves freely. Caulk the stop bead if necessary and touch–up the paint.