How big does a Fire Exit opening have to be?

[johnv]

Some more advice please!
We have a basement room with currently a single entry down a narrow staircase which turns through 90 degrees over the last 5 steps. We want to use this room as a training/meeting room but the issue of the single exit probably makes it unviable without modification.
At the opposite end of the room to the stairway entry is a large double window. Outside the window the ground comes up to ground floor level but there is a concrete built reveal into which it might be possible to fit a steel escape staircase with the foot of the stairs in front of the left hand window. We could deepen the left hand aperture and replace the window with a glazed door.
My question is, how big should an aperture be to be considered acceptable for use as an escape route?

[kurnal]

How many people may need to use it? Will the persons using the basement be fully ambulant and reasonable fit or could there be a broad range of users?
The answer to these questions will determine reasonable solutions to the problem. On the other hand if its a small room and has direct access to outside at the head of the existing stair without going through another room it may be ok with a single exit.

[johnv]

Thanks for the reply kurnal.

There will be 7 or 8 persons including the trainer for training courses, probably 5 or 6 for meetings. All people will be ambulant with reasonable levels of fitness. We certainly would not envisage taking people into the room who could not manage the stairs unaided.

The room is approximately 25 feet square with a low ceiling, about 7 1/2 feet. The existing stairway leads to a short corridor onto which one door from an office opens and an open staircase comes down from the first floor. This corridor, about 12 feet long exits through a door into what will be a dining room/ conservatory with a left turn towards a final fire exit which will be about 10 feet away.

Hope this helps and does not muddy the waters too much.

John

[kurnal]

Is there an exit from the corridor without going through the dining room/ conservatory?

[johnv]

No. The only exit is as I described.
John

[kurnal]

Then the best answer to your question would be  750mm door leading to a 800mm staircase complying with approved document B1 and  K.

Now having said that if you had asked before Oct 1st I could have referred you to the guidance contained in the "fire Precautions Act guide to existing places of work" that require (blue guide) or dont require (red guide) a fire certificate ISBN0-11-341079-4. The guidance allowed for window exits in some exceptional  situations- with  a window at least 850x500mm, steps up to either side with handrails  (No point making them wider than the window) sill no more than 1.1m above the ground and simple fastenings. I stress exceptional circumstances for up to 10 able bodied persons not being the general public according to the guidance.

There is no reference to window exits in the current guidance. But your risk assessment may consider this earlier standard as a possible benchmark as there are many buildings designed to this spec and they cant have all become unacceptably dangerous overnight on September 30th.

Whatever you decide- the options appear to be to provide an additional exit or safeguard the existing single route of exit via the dining room- best value for money may be determined by also considering the safety of people on the first floor - if they too have to pass through the dining room to make their escape then would other control measures such as full detection and control of fire risk in the escape route give best value for money?

[johnv]

Thanks again kurnal.

The info is great and we would be able to accomodate the old recommendations within the existing window opening. Having a secondary emergency exit give the restrictions of the primary route is our ideal solution.

As for the staircase from the first floor, it is to be converted into a fire escape route as an alternative for the primary exit for a single room. In the event that it would be used it would be by usually just one person.

John