Are window restrictors necessary?

What are window restrictors?

Window restrictors are safety devices fitted within a window frame that prevent the window from being opened past a certain point.

There are a wide range of window restrictors available, and it is important to get the right device for your system.

Having window restrictors in family homes allows for ventilation throughout the house without the risk of anyone falling out and harming themselves.


Children under five are most at risk of falling from an open window and so it is recommended that homes with children below this age have a window restrictor.

Window restrictors can also increase the security of your home by preventing entry through open windows.

Sieger slim casement window open with limiting window restrictor

What are the types of window restrictors?

A limiting restrictor makes it so an active sash can only open as far as a certain point by having a maximum number of opening stops.   

Holding restrictors are mechanical devices that can hold the active sash open at a certain point. This includes peg stays that allow the window to be fully open when the restrictor is not manually put in place.     

For windows such as the Sieger 70 Tilt and Turn Window, a reverse restrictor can be used to the window opening at certain points. This mechanical device holds the reversed active sash securely for cleaning.   

A safety restrictor is a mechanical device that limits the initial movement of an active sash to a predetermined position. Sieger’s safety restrictors have a maximum opening of 100mm. This restrictor prevents accidental passage through a window.

It can come in multiple designs such as a metal device or a device with a robust cable. These restrictors are lockable with a key, so the restrictor can be removed and the window fully opened.   

Child safety restrictors have a maximum opening of 89mm.  Similarly to a safety restrictor, this mechanical device limits the movement of an active sash but has a smaller opening. This device prevents passage of children up to 12 months old.

Sieger tilt and turn window
types of window restrictors

Sometimes window restrictors are a legal requirement. In certain buildings such as workplaces, a risk assessment must be carried out to assess if window restrictors are necessary.

Under health and safety legislation, window restrictors are required where people who are vulnerable to the risk of falling have access to windows.

This means all windows above ground level which do not have another fall prevention safety measure in place, such as a balcony or  balustrade should have a restrictor.

Examples of places which need restrictors include but are not limited to hospitals, care homes, schools, colleges, universities, hotels, rental properties, homes with small children and the workplace.


All window restrictors must meet the current British Standards BS EN 14351-1 which is the European Standard for windows and doors and BS EN 13126-5 which specifies the requirements and test methods of devices that restrict the opening of windows.


For more information contact our technical team or book a showroom visit where you can discuss your project in person and see the Sieger window systems.

To talk to the team, call 01494 722 882 or email [email protected]

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