A bedroom above ground floor usually needs a window that can double as an emergency exit. The dimensions are specific, and worth checking before you order.
Under Building Regulations Part B, habitable rooms that do not have an alternative escape route — most commonly bedrooms above the ground floor — generally need a window that can serve as a means of escape in a fire. This is a straightforward requirement to meet, but it is easy to overlook when choosing a window style or replacing a large opening with a differently configured one.
The rule affects which opening style you can specify in an affected room and how the window is positioned, so it is worth checking early rather than after manufacture.
An opening must satisfy the height, width and area figures simultaneously — a wide but shallow opening that meets the area but not the height, for instance, does not comply. The measurement is of the clear openable area, not the overall window size, so frame profile and opening mechanism both affect whether a given window passes.
Ground floor habitable rooms with a door leading directly outside are generally exempt, since the door itself provides the escape route. Bathrooms and other non-habitable rooms are not normally subject to this requirement.
| Opening style | Escape suitability |
|---|---|
| Side-hung casement | Usually straightforward to meet the requirement if sized correctly |
| Top-hung casement | Can meet it, but the opening geometry needs checking carefully |
| Fixed pane combined with an opener | Compliant provided the opening light alone meets all three dimensions |
| Tilt and turn, turned position | Can provide a large escape opening, often exceeding the minimum comfortably |
| Sliding sash | Depends on the sash travel; some historic sash proportions need checking |
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