What This Requirement Covers
Approved Document K requires measures to prevent falls from windows, particularly in buildings where children may be present. Window restrictors limit the opening of a window to prevent a person from falling through the opening, while still allowing the window to be opened fully for emergency escape or cleaning.
Key Requirements
When Window Restrictors Are Required
- Windows with a cill height below 800 mm above the floor in any building where the drop outside exceeds 600 mm
- In buildings where children under 5 may be present (dwellings, schools, nurseries), restrictors are required on all openable windows above ground floor unless the window is required for emergency escape
Restrictor Requirements
- Window restrictors must limit the opening to no more than 100 mm in the first instance
- The restrictor must be robust enough to resist a child leaning against it
- A key-operated or two-handed release mechanism must be provided to allow the window to be opened fully (for emergency escape, cleaning, or ventilation)
- The release mechanism must be operable by an adult without tools
Emergency Escape Windows
- Where a window is designated as an emergency escape window (Approved Document B), it must be capable of opening fully
- The restrictor must not prevent the window from being opened for escape in an emergency
- A key-release restrictor is acceptable provided the key is readily available (though not to young children)
Guarding Alternative
- Instead of window restrictors, guarding (a rail or barrier) can be provided in front of the window to prevent falls
- The guarding must be at least 800 mm high and must not be climbable
Practical Compliance Tips
- Check all windows with low cill heights at the design stage and specify restrictors where required
- Specify restrictors that are robust and tamper-resistant; cheap restrictors can fail under load
- Ensure the restrictor allows the window to be opened fully for escape; a restrictor that prevents full opening on an escape window is non-compliant with Part B
- In new dwellings, consider specifying windows with integrated restrictors from the factory
- Brief occupants on how to release the restrictor for cleaning and emergency escape
- In schools and nurseries, use restrictors that cannot be released by children
- Inspect restrictors annually and replace any that are damaged or not functioning correctly