Window restrictors: keeping children safe at upstairs windows, and how to fit them

Every year, children are hurt falling from windows, and most of those falls are from first- and second-floor bedroom windows in ordinary homes. A restrictor costs little, fits in minutes, and still lets you open the window for air. This guide covers the types, how to fit one, and the fire-escape rule you must not break.

The short answer

A window restrictor limits how far a window opens, usually to a gap a child cannot fit through, while an adult can release it in seconds. Fit restrictors to any upstairs window a child could reach, especially where the sill is low or furniture sits under the window. On bedroom windows that are escape routes, use releasable restrictors that need no key.

Which restrictor suits your window

Window	Restrictor type	Notes
uPVC or aluminium casement	Cable restrictor	A steel cable with a lockable or push-button release, screwed to frame and sash
uPVC tilt and turn	Built-in or handle restrictor	Often already part of the hardware; check the handle positions
Timber sash	Sash stop	Screwed into the frame, blocks the lower sash after a small opening
Friction-hinged casement	Restrictor hinge	Replaces the existing hinge with one that catches at a set opening
Top-hung or awning window	Cable or arm restrictor	Fit to the side so it does not catch on blinds

For tilt and turn windows, the tilt position is itself a safe ventilation setting, and many have a lock on the handle.

How to fit a cable restrictor

1. Choose the position. Fit it to the side of the window away from the hinges, at a height you can reach but a child cannot easily.
2. Open the window to the gap you want and hold the cable across from frame to sash. Mark both screw positions.
3. Check you are not drilling into glass edges or steel reinforcement. Fix to the frame face, not the glass beads.
4. Screw the frame plate to the fixed frame with the screws supplied.
5. Screw the sash plate to the opening sash.
6. Clip the cable in and test by pushing the window open hard. It should stop firmly at the set gap.
7. Test the release. An adult should be able to free it quickly, and it should not need a key on an escape window.

On sash windows, fit sash stops into the side of the frame above the lower sash, so the sash meets the stop once raised the chosen amount.

Worth knowing: a restrictor is only as safe as the habit around it. Keep beds, toy boxes and chairs away from windows, because children climb, and a restrictor left unclipped does nothing.

The fire-escape rule

Many upstairs bedroom windows are also the escape route in a fire. On those windows:

• the restrictor must release by hand, quickly, without a key or tool;
• everyone in the home old enough should know how it releases;
• the window must still open wide enough to climb out once released;
• keys for locking handles should be kept near the window, not on a key ring.

If you are not sure whether a window is an escape window, ask at survey. When we fit new casement windows, escape windows get egress hinges that open wide for escape.

For landlords and letting agents

Fall hazards from windows are one of the things a council checks in rented homes. On upper floors with low sills, releasable restrictors are the normal expectation, and they should be checked at every inspection: cables frayed, screws loose, releases jammed. If you manage several properties, our trade accounts page explains how letting agents and landlords book repair work across a portfolio.

Need them fitted?

We fit restrictors to uPVC, aluminium and timber windows, and replace worn hinges and broken handles while we are there through our uPVC window repair service. If a window will not lock or a restrictor has snapped, send a photo on WhatsApp or call 07915 903485.

Related: how to fix a uPVC window that won't close and trickle vents explained, for fresh air without opening the window at all.