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A broken or frayed sash cord causes your window to drop, jam, or refuse to stay open. We carry out professional sash cord replacement across London — restoring smooth, balanced operation to all types of timber sash windows.
Sash cords are the woven ropes that connect your window sashes to the counterbalance weights hidden inside the box frame. They are what allow the upper and lower sashes to slide up and down smoothly and stay open at any height.
Traditional sash cords are made from twisted cotton or flax and are remarkably durable — original cords on well-maintained Victorian and Edwardian windows can last 30 to 50 years. Over time, however, exposure to moisture, paint, and general wear causes the fibres to rot, fray, or snap entirely. When a cord breaks, the sash drops to the bottom of the frame and is held shut only by the remaining intact cord on the other side. If both cords on a sash fail, it will not stay open at all.
If your sash drops as soon as you let go, one or both cords on that sash have snapped. The counterweight is no longer holding the sash in balance.
A window that requires significant effort to slide indicates the cord is frayed or the weight has become disconnected. The balance has been lost.
If the sash tilts to one side, the cord on that side has failed while the other remains intact. The uneven tension pulls the sash out of square.
Sometimes you can see the cord hanging loose in the side channel, or dangling from the pulley wheel at the top of the frame. This means it has parted from the weight.
A broken cord can cause the sash to jam in the closed position, as the weight has dropped to the bottom of the box and the cord has bunched up inside the frame.
A sash that sits unevenly or drops slightly will no longer seal correctly in its frame, leading to new draughts and rattling that were not there before.
Our sash cord replacement service is carried out by experienced joiners who have worked on London timber windows for years. We always replace all four cords on the affected window at the same time — not just the broken one. This is important because if one cord has failed, the others are often at a similar stage of wear and will follow shortly. Replacing just one cord is a short-term fix.
We use high-quality waxed cotton sash cord, which is the correct material for timber box sash windows and significantly outperforms modern synthetic alternatives in both lifespan and pulley performance.
We carefully remove the staff beads and parting beads from the window frame to release both sashes without damage to the surrounding timber or decoration.
With the beads removed, we slide out the lower sash, then the upper sash. We open the pocket covers at the base of the frame to retrieve the cast iron counterbalance weights inside.
We check the pulley wheels for wear and ensure they spin freely. Any old cord debris, paint, or build-up is cleared from inside the box frame before re-cording begins.
New cords are threaded over the pulleys, knotted securely to the weights, and fixed into the cord groove on each sash using the correct ring-shank nails. All four cords are replaced.
Both sashes are rehung in the correct order, the beads are refitted and pinned, and the window is tested across its full range of movement to confirm smooth, balanced operation.
With the window already disassembled, it is the ideal time to fit professional draught proofing brush seals. Many of our customers combine both jobs to save on labour costs.
Sash cord replacement is one of the most straightforward and cost-effective repairs we carry out. Prices depend on the number of windows, ease of access, and whether any additional work is needed such as pulley replacement or timber repairs.
Single Window
£100–£175
All four cords replaced. Pulleys checked and cleaned.
Multiple Windows
From £80/window
Better value when combining multiple windows in one visit.
With Draught Proofing
£200–£350
Cord replacement plus full draught seal installation per window.
All prices are indicative. We provide a free written quotation after a site survey. There are no call-out fees and no obligation. For a full breakdown of our repair costs, see our sash window price guide.
Replacing a sash cord is technically possible as a DIY project, and the material cost is minimal. However, in practice most London homeowners find the job more involved than expected. The difficulties include:
A professional job takes around 2–3 hours per window and comes with the assurance that the balance is set correctly, the cords are appropriate for the weights, and nothing has been damaged in the process. For most homeowners, the cost of a professional repair is money well spent — especially on period properties where the original beads and joinery are irreplaceable.
For a standard timber sash window, cord replacement takes approximately 2–3 hours per window. Most single-window jobs can be completed in a single morning visit. For a whole house of windows, we typically spread the work over one or two days depending on access.
No — the window frames remain in the wall. Only the sashes (the sliding parts) are removed during the repair. The process is clean and contained, with no major disruption to your property. We use dust sheets as standard.
Good-quality waxed cotton sash cord installed correctly will last 20–40 years with no maintenance required. The longevity depends on how frequently the window is used, the condition of the pulley wheels, and whether any water ingress is present in the box frame.
Yes — sash cord replacement is classed as a like-for-like repair and does not require planning permission or listed building consent. We work on period properties across London regularly and understand the care required when working with original Victorian and Edwardian joinery. See our period property window repairs page for more information.
We inspect the pulleys as part of every cord replacement. If a pulley wheel is seized, corroded, or missing, we will advise you and can replace it during the same visit at a small additional cost. Seized pulleys cause cords to wear quickly, so this is worth addressing at the same time.
In almost all cases, yes — a sash that has suddenly stopped staying open has lost one of its counterbalance cords. It is the most common cause of this fault on timber sash windows. Occasionally a weight may have come off the cord at the knot, or the cord has jumped out of the pulley wheel, but these are all variations of the same underlying problem and are resolved in the same way.
We carry out sash window repairs across all of Greater London, with a particular focus on North, Central and East London boroughs including Islington, Hackney, Camden, Haringey, Lambeth, Southwark, and Kensington. View our full coverage area or call us to confirm your postcode.
Call us or get in touch for a free site survey and written quotation. No call-out fee, no obligation.
Full repair service for all types of timber sash window faults across London.
Best combined with cord replacement — we fit brush pile seals while the window is already disassembled.
A full guide to our repair, restoration and replacement costs in London.
Here at Golden Ratio Windows we have built up an excellent reputation in our local area by offering the most comprehensive and expert service in London. From the planning stage to the finished article; we are with you every step of the way, making sure that whatever the task, you are completely satisfied with the end result.
Get a Free QuoteWith so many years working in the trade, we are happy to answer any queries and provide quotes for any work that you are looking to have done. Rest assured that you will be receiving a professional, yet personal service. If you are in need of any work in London or the surrounding areas, get in touch.
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