How To Replace Window Sash Cords

Over time, sash cords can wear out or break, making the window difficult or dangerous to use. In this article, we’ll guide you through replacing window sash cords and help you restore your windows to their former glory. This Old House general contractor, Tom Silva, demonstrates the step-by-step process.

For other sash window repairs, read our complete guide to repairing sash windows.

Signs of Worn Sash Cords

Look out for these indicators that your window sash cords may need replacement:

• Windows that are difficult to open or close
• Sashes that won’t stay up when opened
• Visible fraying or breakage of existing cords
• Windows that slam shut unexpectedly

Tools and Materials Needed To Replace Window Sash Cords

To replace your broken or missing sashes, gather these tools and materials:

• Flat pry bar
• New sash cord
• Replacement sash weights (if necessary)
• Screwdriver
• Small screws or hex nuts (for weight attachment)
• String
• Utility knife

Steps To Replace Window Sash Cords

Follow these steps to replace your window sash cords:

1. Remove the Window Sashes

Removing the window sashes can be a delicate task. Handle the glass panels carefully to avoid breakage. Once the sashes are out, take a moment to inspect them for any signs of damage or wear that might also need addressing. Remove the lower and upper sashes from the window frame to access the sash cords.

1. Unscrew and remove the window stops from each side jamb.
2. Carefully remove the bottom sash from the frame.
3. Use a pry bar to gently remove the parting bead, which separates the upper and lower sashes.
4. Remove the upper sash from the frame.

Pro Tip: When raising the lower sash to swing it out, pull the cord out of its groove in the sash stile and tie a figure-eight knot in the end. This keeps the cord from being pulled down into the weight pocket by the counterweight — a mistake that can turn a simple repair into a much more involved one.

Technique Detail: Before prying off the inside stops, use a utility knife with a fresh blade to score along the joints where the stop meets the side casing and the sill. This breaks the paint film and prevents tearing or chipping the surrounding woodwork. Insert a stiff putty knife in the joint about halfway up the window opening, then gently bend the stop and insert a pry bar in the gap above the knife. Work the two tools down toward the sill, putty knife in the lead, until the stop is free. Pull any finish nails out through the back of the stop to avoid splintering the face.

2. Access the Sash Weights

Accessing the sash weights can be tricky, especially in older homes with brittle wood. Be sure to have a firm grasp on the weights to prevent them from dropping into the wall cavity, which can complicate the process further. The sash weights reside within the window frame.

1. Cut the old sash cords on both sides of the window frame.
2. Tie knots in the cut cords to prevent them from falling into the wall cavity.
3. Locate and unscrew the access panel on the side jambs to reveal the weights inside the void of the wall.
4. Remove any sash weights that have broken free from their cords.

3. Prepare the New Cords

Before installing new cords, you’ll need to prepare them for threading through the pulley system.

1. Attach a length of string to any remaining sash cords.
2. Use this string to pull the old cord and the attached new cord through the pulley and access hole.
3. Cut the new cord free from the old one and tie it to the sash weight.
4. Carefully lower the weight back into the wall cavity.

For pulleys without existing cords:

1. Tie a small weight–such as a screw or hex nut–to a string.
2. Feed this weighted string over the pulley and into the wall cavity.
3. Use the string to pull the new sash cord into place.

Take extra care to secure the cords to the weights firmly, as a loose knot can result in the cord detaching and the window malfunctioning again.

4. Attach Cords to the Sashes

With the new cords in place, it’s time to reattach them to the window sashes. Double-check your measurements and knots to confirm the cords are both secure and of the correct length.

1. Hold the top sash in the window frame and measure the cord length needed.
2. Cut the new cords to the appropriate length, allowing extra for tying.
3. Securely tie the new cords to each side of the sash.
4. Repeat this process for the bottom sash.

Finding the Right Length: With the weight bottomed out and the sash in the open position, pull the cord down to bring the weight all the way to the top until it stops. Then let it come back down about three inches. Mark the cord where it lines up with the hole in the sash stile — that’s where you’ll tie your knot. Cut the cord, allowing a little extra beyond the mark for tying.

On the edge of each sash, you’ll find a dado — a narrow groove — with a hole at the bottom. That’s where the rope sits. Push the cord into the dado, line up your knot at the bottom of the hole, and to keep it in place while you reinstall the sash, drive a small nail through the knot to pin it securely.

5. Reassemble the Window

Once the cords are attached, you can put the window back together. A window should open and close smoothly, and the sashes should stay in any position you place them.

1. Reinstall the top sash into the frame.
2. Replace the parting bead to separate the upper and lower sashes.
3. Install the bottom sash.
4. Reattach the window stops to hold everything in place.

Tips for Successful Sash Cord Replacement

Keep these tips in mind for a smooth replacement process:

• Work on one side of the window at a time to maintain stability.
• Mark cord lengths carefully to promote proper balance.
• Test the window’s operation before fully reassembling to make adjustments if needed.
• To prevent future issues, consider replacing all cords simultaneously.

Always prioritize safety by wearing protective gear such as gloves and safety glasses. Remember to keep your workspace clear of hazards and have a stable ladder if you’re working at height.

Pro Tip: One of the hardest parts of replacing a broken sash cord is fishing it over the pulley and down into the weight pocket. A technique featured in This Old House Magazine recommends making a messenger line by knotting one end of a length of light twine and sliding four or five small nuts against the knot to add weight. Then tie the twine’s other end to the new sash cord and let the weighted end pull everything into place.

When To Call a Professional To Replace Window Sash Cords

While replacing window sash cords is a manageable do-it-yourself project for many homeowners, there are situations where professional help may be necessary:

• If the window frame is damaged or rotted
• When dealing with very large or unusually shaped windows
• If you’re uncomfortable working with tools or heights
• When multiple windows need cord replacement, which can be time-consuming

Professionals have the expertise and tools to handle complex window repairs efficiently. If you encounter unexpected challenges or if the scope of the project feels overwhelming, contacting a professional can save you time and frustration.