Means of Escape Â– Flats with more than one level, with a floor at more than 4.5m over ground Â– Part 6
When considering means of escape in flats, the situation can be further complicated where the flats have more than one storey, e.g. maisonettes or cross-over flats, where one storey is over 4.5m from the ground or main exit level. In these instances, however, the main principles of alternative exits and protected exit routes are still used.
Current benchmark design guidance, for example, approved document B/BS 9991 provides approaches to assist with ensuring fire safety provision is made. This blog will consider each in turn:
1) The provision of an alternative exit from each habitable room that is not on the entrance level.
On an upper floor of a flat, each habitable room has its own alternative exit, which would therefore negate the requirement to have a protected upper landing and stairway. The entrance hall itself only requires protection if the travel distance from any point within the flat’s upper floor rooms to the main exit door exceeds 9m, or if that room does not have an alternative exit.
2) The provision of a single alternative exit from each level not being the entrance level, plus the provision of a protected landing and hallway.
There are situations where a single alternative exit provision on the upper floor may be an acceptable solution when coupled with a protected landing and hallway. The alternative exit could lead from a habitable room or from the upper landing itself.
The situations where it may be applicable are:
Where all habitable rooms on that floor are directly accessible from a protected entrance hall and landing.
A fire-resisting partition is present at the base or top of the stairway, effectively separating the entrance level from the upper level with alternative exit. It would only be necessary to have a protected landing where the travel distance between any room on the upper level and the alternative exit exceeds 9m.
The alternative exit is within a room where pass doors are provided between habitable rooms on this level, therefore negating the need to have to use the stairway enclosure to reach an alternative exit.
There will, of course, be flats – particularly cross-over flats where fire safety design can be more complicated by necessity – which do not fit into these situations neatly. The same principles apply, however, and each case should be considered individually and with care.
3) Provision of a protected route plus provision of automatic detection system
This potential solution would be applicable within flats where the vertical distance between the entrance level of the flat and any floors above or below does not exceed 7.5m. The solution requires that the entrance hall, stairway and landing are protected and that additional automatic detection in all habitable rooms should be provided to Category LD1 standard.
4) Provision of a protected route plus provision of an automatic suppression system.
The fourth option has the same principles as the third, but in this case an automatic suppression system is installed throughout, instead of an automatic detection system. A sprinkler or water misting system must be installed throughout the flat, together with an automatic detection in the circulation spaces to Category LD3 standard.
Next week’s blog will look at escape routes in common parts of blocks of flats and escape from flats with internal corridor or lobby approach.
In the meantime, if you have any queries about this blog or would like to know more about the Complete Fire Safety Management online fire risk assessment platform, please contact Peter Gyere in the first instance on 0208 668 8663.
The Complete Fire Safety Management Platform is the only fully comprehensive online fire risk assessment and fire risk management platform. Our aim, at CFSM, is to make the process of becoming fire safe, straightforward and, to use our expertise in fire risk assessment and fire safety management to guide you through each step, resulting in your premises meeting all legal, insurance and ethical fire safety considerations.