Sash Window Won’t Stay Open

A sash that drops may have a broken cord, missing or undersized counterweight, a seized pulley or altered glazing weight.

Safe checks

Without removing the sash, inspect visible cords for fraying and listen for unusual pulley noises. Avoid standing beneath an unsupported sash or wedging it open with loose objects.

Likely remedies

Repairs may involve replacing cords, servicing pulleys and selecting appropriate counterweights. A professional should assess a sash that falls suddenly or has loose glass.

What the symptom suggests

If the lower sash falls when released, its counterbalance is no longer doing enough work. The cause may be a broken cord, a missing or undersized weight, an obstructed weight pocket or a pulley that does not rotate freely.

Simple observations

Notice whether the sash falls evenly or drops at one corner, whether cords are visible, and whether it moves smoothly for part of its travel. Do not hold the sash open with your hand while reaching into the case.

Why glazing changes matter

Replacing small historic panes with thicker glass can alter the sash weight. A window that worked before reglazing may need its balancing system reassessed rather than simply lubricating the pulley.

Repair options

The correct solution depends on the fault: renewing cords, freeing or replacing pulleys, clearing a weight pocket or adjusting counterweights. A competent repairer should confirm the sash can be opened and closed without uncontrolled movement.

Avoid unsafe shortcuts

Do not rely on improvised wedges, nails through the sash or friction alone to support a heavy window. These can damage timber and create a falling-sash hazard.