Over the years, a considerable amount of legislation has been created governing the safety features of windows. These features help prevent accidental (or deliberate) falls through open windows or from balconies, or from falling against glazing. Regulations also govern ventilation and heat loss, as well as facilitating fire safety and a means of escape in an emergency.


Replacement glazing has been governed by the Building Regulations since 2002, and is a "controlled fitting" which must meet certain standards.               


The legislative requirements governing windows are detailed in the Building Regulations. These take precedence over British Standard BS 8213-1:2004, which provides "recommendations on the design, construction, operation and maintenance of windows" - designed to help ensure their safe use for occupants and passers-by.


Thermal heat Loss

New windows must comply with requirements governing the amount of heat that can pass through glazing, measured as a U-value. This must not be exceeded.


Safety glazing

If a new window is situated in a 'critical area', it must comprise safety glazing.

Safety glazing must be used in the following critical areas:

  • Any glazed area within a window situated 800mm from the level of the floor.
  • Any glazed area within a window that is 300mm (or less) from a door and up to 1500mm from the level of the floor.
  • In a glazed door up to 1500mm from the level of the floor.


What is safety glazing?

Safety glazing must break safely - if it breaks. It should be laminated or toughened Class C safety glass and comply with BS6206. Regular wired glass is not safety glass. In some cases, ‘annealed’ glass can be used as safety glass, but only if it is thick enough.



Windows (and doors) possess the capability to ventilate a home. How much ventilation a window must be able to provide depends on the use of the room. For instance, an area where steam may be produced, such as a kitchen or bathroom, may require more ventilation than, say, a living room or bedroom. Windows or mechanical fans may provide this ventilation capability.


Fire safety

Windows serve two main purposes during a fire: to limit the spread of the fire (by having fire resistance properties); and to provide a means of escape.


Fire resistance

External windows may be required to have fire resistance properties to limit the spread of fire to adjacent buildings. External windows may also be required to be fixed shut. To what extent windows must have these features depends on how close they are to the boundary.


Means of escape

Any replacement window should provide the same or greater means of escape as the window it replaces - i.e. the size of the opening should not be smaller than the previous window.

However, if the previous window provided a means of escape that was larger than necessary, the minimum general criteria for egress (emergency escape) windows are as follows:

  • Width and height must not be less than 450mm
  • Clear openable area of at least 0.33m2
  • The bottom of the openable area must not be higher than 1100mm above floor level.


More on British Standard BS 8213-1:200

British Standard BS 8213-1:200 is aimed at people involved in the specification, design, choice and operation of windows. This group includes building owners, as well as house-builders, architects, public authorities and others.

This code of practice includes guidance on:

  • Reach capabilities
  • Safety restrictors
  • Design for safe cleaning
  • Maintenance of external and internal glazing at height
  • Safe working practices in the use of portable ladders


Window specifications for manufacturers

There are many specifications for window manufacturers covering material and performance requirements, because a wide variety of materials are now used in modern windows.


Practical tips for improving window safety

Existing windows in your home can be strengthened by applying certain DIY films. These films can help prevent glass from shattering (in the event that someone falls through a window), and make it harder to break (in the event of attempted burglary).


Older windows

Older windows, while often visually appealing, often provide limited safety features. You might consider replacing your windows if they:


  • Would be difficult or impossible to escape from in the event of an emergency
  • Might be easy to break in to
  • That permit too much noise
  • Lose too much heat
  • Provide insufficient ventilation