How to Replace a Broken Sash Cord in a Double Hung Window (Step-by-Step Guide)

Few things date a beautiful old window faster than a snapped sash cord. The window jams, slams, or has to be propped open with a book — and the culprit is almost always a length of cotton cord that quietly rotted away inside the frame. The good news: replacing a sash cord is one of the most satisfying repairs a home owner can do, and done properly with the right cord, you shouldn't have to do it again.

Why sash cords fail

Traditional sash cord is 100% cotton. Cotton is beautiful and authentic, but UV light and moisture break it down over time. The cord frays where it runs over the pulley, then one day it lets go and the sash weight drops inside the box frame with a thud. If one cord in a window has failed, its partner is usually not far behind — always replace cords in pairs, or better still, all four.

What you'll need

• Replacement sash cord — as a guide, 10 metres covers one standard double hung window with some to spare
• A screwdriver or chisel to remove the staff beads
• Pliers, plus small nails or screws
• A "mouse" — a small weight such as a screw tied to string, for feeding the new cord over the pulley

The steps

1. Remove the sashes. Gently prise off the staff beads and lift out the bottom sash, then remove the parting beads and lift out the top sash.
2. Open the weight pocket. Locate the pocket in the side of the box frame and lift out the sash weight.
3. Feed the new cord. Drop your mouse over the pulley and down into the pocket, tie on the new cord, and pull it through.
4. Attach the weight. Secure the cord to the weight with a strong knot, then cut the cord so the weight hangs about 50mm above the pocket base when the sash is fully raised.
5. Fix the cord to the sash. Nail or screw the other end into the sash's cord groove, refit the sashes and beads, and test the balance.

Choose a cord that won't send you back up the ladder

This is where most repairs go wrong: replacing rotted cotton with more cotton. Our waxed cotton sash cord, made in England by James Lever & Sons — the same family firm since 1856 — looks completely authentic on the outside, but carries a concealed poly core that resists the UV degradation that kills ordinary cord. Old-world looks, modern strength.

Read the story behind the cord here, or browse the full James Lever & Sons heritage cordage collection.