Basement fire doors

[SidM]

Why are fire door(s) required to a basement even if the basement is not on an escape route.  Is two 30 minute doors or one 60 minute door for: (a) life safety (b) firefighter safety or (c) property protection.  If the basement is on an escape route, why is it that, generally speaking, one FD30S will not be adequate?

If anyone could provide a reference(s) of what the reason(s) are for separating basements from the rest of the premises.

[nearlythere]

Why are fire door(s) required to a basement even if the basement is not on an escape route.  Is two 30 minute doors or one 60 minute door for: (a) life safety (b) firefighter safety or (c) property protection.  If the basement is on an escape route, why is it that, generally speaking, one FD30S will not be adequate?

If anyone could provide a reference(s) of what the reason(s) are for separating basements from the rest of the premises.

Normally there are no external windows for a fire to breech and enable some ventilation. The weakest point will therefore probably be any internal doors thus the extra heat and smoke protection.

[kurnal]

Basements are difficult areas to ventilate. You can't just open a window. They tend to be infrequently visited so fires can often develop undetected in their early stages.  
For these reasons , for most purpose groups all the elements of structure of a basement require at least a one hour standard of fire resistance.  

For means of escape two doors, one top and bottom are better than one at the top. If there is a single door at the top persons escaping from the basement would  have to travel through the smoke  and heat layer as they ascended the stair.

On the other hand if the single door was at basement floor level as they opened it to pass through smoke would enter the staircase and rise due to bouyancy so the upper levels of the staircase would also be jeopardised- the protected staircase may not then be a place of relative safety. Could we afford not to count the travel distance in the staircase in such circumstances>

Two doors create an air lock overcoming these problems, and also help fire fighters.

Two half hour doors are better than a single 1 hour door for firefighters because the air lock provides a good safe bridgehead for firefighting and means that firefighters do not have to pass down through the heat layer as they access the basement for fire fighting purposes, enabling them safely to enter the basement and extinguish the fire- and retreat safely if it turns pear shaped.

[SidM]

Thanks guys; much appreciated.

[SidM]

The DCLG guides talk about any  stairway that extends from the basement to the upper floors should be separated at basement level by fire resisting lobby or corridor between the basement and the stairway. 

Another paragraph then talks off separating the ground floor from the basement with two 30 minute fire doors.

Are both these paragraphs trying to achieve one and the same thing or two different things? 

[BB]

It also depends on the risk within the premises.....do you need 2 x 30min fire doors for a low risk fish gutting process in the basement compared to say a high risk spray booth. Like everthing else up under the Fire Safety Order it's down to a risk assessment.