NFPA 92A area leakage

[Ciaci]

Hi all,
Designing a stairwell pressurized with the use of NFPA 92A, there is this table which represents the Leakage Areas of buildings. I particulary appraciate the fact that reference are presented, but I have a question: how can I say if a wall is tight average or loose? Is the choice of loose wall always a safe assumption? I am afraid that assuming a wall too loose can lead to a flow rate that when the doors are closed can bring to pressure difference that does not allow to open the doors. I don't know in my geographic area people that are expert about stairwell pressurization, so I hope that someone can give me some hints.

 

[UFT12]

I doubt you will find better guidance on this than your own judgment.

Loose should be used for old buildings or when you know/feel the walls/floors are of pure quality.
Tight should be used for good quality build, heavy duty concrete or areas in basements etc.
Average should be used for anything in between or when you feel that a tight building through time may end up "average".

All in all, unless you have an indication or strong belief for a specific category, average is a good starting point and see what do you get out of it.

Side note, if by any chance you can find a paper of the work done by the references cited, maybe you could find better explanations about those three categories.

 

[Ciaci]

I asked this because I was wandering if someone perform test such as doorfan test in the stairwell before the design. I was wandering if it is a best practice