Replacing a broken cord on a sash window is a complex job that requires a good deal of skill and precision work. Most people would be best advised to have it done professionally, but it should be within the capacity of a skilled DIYer such as Handy Squad, though you should make sure you have an assistant.
Materials and Preparation
Sash cords can be a variety of diameters and materials (waxed or unwaxed hemp, synthetics etc.) and it’s important to match at the least the diameter of the new cord to the old one. Usually, you’ll buy a pack of sash cord that should have enough for your use. If you need to estimate what you need, buy two lengths for each sash that are 167% of the distance from top to sill.
Always remove the lower sash first, and use a mallet and chisel to remove the staff beads from each side. Once you have one loose, the remaining beads should pull out. Tie string round the cords near the pulley and cut the cords below it, running the string over the pulleys. The lower sash can then be removed.
Prise out the parting beads and pocket covers and remove the upper sash, then take out the weights and label them immediately. They may not be quite identical, so it’s important to put them back in the right place. The old cords can then be removed.
Replacing the Cords
Always replace the cords on the upper sash first, so it can be put back before you tackle the lower sash. With a 50mm screw or nail tied to a piece of string, feed it through the hole above the pulley so it drops into the weight compartment.
Attach one of your lengths of cord to the string and push it over the pulley and down, recovering it from the pocket and feeding it through the hole above the weights, having removed the string. Tie the cord in a figure-of-eight knot and push the end into the cavity above the weight, after which the weights and the pocket covers can be replace. Then repeat on the other side.
Replacing the Sashes
After replacing the upper sash, reposition the parting beads with a mallet, replacing any that are damaged. With the lower sash resting on the sill, raise the weights to their highest level and tie a knot in each cord level with the knot hole on each side of the sash.
Tap the staff beads back with a mallet and secure them with 25mm oval nails, but test that the sash works smoothly before hammering them all the way in. All that’s left then is to repair the windows with wood filler and repaint them.
Or, if all this sounds too much, you could always call us at The Handy Squad: 0800-0 12 12 12.