Escape windows: sizes and rules
When an escape window is needed and the clear opening guidance in England.
When is an escape window needed?
In England, Approved Document B guidance calls for an escape window in habitable rooms on the first floor of a house, other than kitchens, where there is no protected stair. Other layouts have their own rules, so check the fire safety strategy for the property.
How big must it be?
The guidance gives an unobstructed openable area of at least 0.33m², at least 450mm high and 450mm wide, with the bottom of the opening no more than 1100mm above the floor.
How can a casement meet the escape guidance?
Use egress (escape) hinges on a side-hung sash so it opens to a full right angle, and size the sash so the clear opening meets the guidance. Give us the clear opening you need; the quote shows the clear opening each sash gives, and the installer confirms it meets the requirement.
Can a replacement make things worse?
The guidance says replacement windows should not reduce the escape provision that was there before. Measure the existing clear opening first.
This guide is general information for trade customers. The person carrying out the work remains responsible for meeting the building regulations and any planning requirements for the specific job.