How to Replace a Sash Window Cord: A Step-by-Step Guide

Sash windows add timeless charm to traditional homes, but like any feature, they require occasional maintenance to keep them in working order. One of the most common window repairs is replacing a broken sash window cord—a task that, while a bit fiddly, is completely manageable with the right tools and guidance.

In this detailed guide, we’ll walk you through how to replace a sash window cord, helping you preserve your windows’ elegance and function. Whether you're tackling a single cord or considering a full sash window replacement, this process is a rewarding home improvement project that restores the usability and beauty of your windows.

Why Replace a Sash Window Cord?

The sash window cord is what allows the sash to move up and down smoothly, held in balance by counterweights hidden within the frame. Over time, these cords can fray or snap from wear, age, or rot—especially in older wooden windows. When one cord breaks, it’s wise to replace both, as the second is likely not far behind.

Replacing sash cords improves your window’s safety, functionality, and aesthetics, and is often more cost-effective than full window replacement.

What You’ll Need

Before starting, gather the following tools and materials:

• Replacement sash cord (waxed hemp or synthetic cord of the same diameter)

• Tape measure

• Chisel or flathead screwdriver

• Mallet or small hammer

• Pincers

• Drill (optional, for screws)

• Screws or nails (for reassembly)

• String

• Small 50mm nail or screw (for guiding the cord)

• Galvanised clout nails (for securing cord if necessary)

• Wood filler (for touch-up)

• Paint (optional, for refinishing)

Choosing the Right Sash Cord

Sash cords come in a variety of materials including waxed and unwaxed hemp or synthetic fibres. It's crucial to match the sash window cord diameter to your existing one. If you’re unsure, take a piece of the old cord to your local hardware store for a perfect match.

To estimate how much cord you’ll need, measure from the top of the window to the sill and add two-thirds of that length. Remember, you’ll need two cords per sash, and it’s best not to cut to length until you're ready to install.

Preparing for Cord Replacement

If you're removing both sashes, label the weights clearly as upper (outer) or lower (inner). They may look identical but often vary slightly in weight—mixing them up can prevent the sashes from gliding smoothly post-installation.

Step-by-Step: How to Replace a Sash Window Cord

Step 1: Remove the Sashes

To replace the lower sash cord, first remove the lower sash itself. If you need to replace the upper sash cord, you’ll also need to take out the lower sash first.

1. Carefully remove the staff beads on both sides using a chisel or screwdriver. Start in the center to prevent corner damage.

2. Once loosened, gently pull the beads free from the mitred joints.

3. If the old cords are intact, tie string near the pulley and cut below it—this allows you to pull the new cord into place using the string.

Set the lower sash aside and detach the remaining pieces of cord from each side using pincers.

Step 2: Remove the Parting Beads and Access the Weights

1. Carefully pry the parting beads from their grooves. These can be wedged, nailed, or screwed in. If you're only replacing the lower sash cord, you may not need to remove these completely.

2. Remove the upper sash if you're replacing its cords.

3. Use a chisel to lift the pocket covers—these give you access to the sash weights.

4. Gently pull the weights out and remove any remaining cord.

Step 3: Threading and Securing the New Sash Cord

Here’s how to thread your new sash window cord:

1. Tie a small nail or screw to the end of a string and drop it through the pulley hole—retrieve it from the pocket.

2. Attach the new sash cord to the string and pull it through the pulley and down to the weight pocket.

3. Remove the string, thread the cord through the top of the weight, and secure it with a figure-of-eight stop knot (see tip below).

4. Tuck the cord end into the weight’s cavity and replace the weight into its pocket.

🛠 Pro Tip – Use a Stop Knot:
To prevent the weight from slipping off, use a figure-of-eight knot. Make a loop about 75mm from the cord’s end, wrap the end around the back to form an eight, then pass it through the original loop.

Step 4: Reassembling the Window

1. Begin with the upper sash if both sashes were removed. Pull cords tight, tie knots, and reinstall it into the frame.

2. Tap parting beads back into their slots. Replace them if they’re damaged.

3. Place the lower sash on the sill. With a helper, raise the weights by pulling the cords upward. Tie knots in the cords aligned with the knot holes in the sash.

4. Secure cords using clout nails if knot holes are worn, and reinstall the lower sash.

5. Finally, reattach the staff beads using oval nails. Don’t drive nails in fully until you’ve confirmed smooth sash movement. Adjust if necessary.

Step 5: Finishing Touches

Once your sash windows are working perfectly:

• Drive all nails fully into place.

• Fill any gaps or damage with wood filler.

• Repaint the window if needed to finish the job professionally.

A Smart Step in Your Home Improvement Journey

Replacing a sash window cord is a practical and satisfying home improvement task that revives the charm and function of your classic windows. Whether you're doing routine window repairs or prepping for a full sash window replacement, learning how to maintain sash mechanisms can save you time, money, and hassle in the long run.

If you're new to window installation or restoration, take it one step at a time—and don’t hesitate to seek help from a professional for more complex projects. But for many homeowners, this is one DIY fix that’s well within reach.