Voids in fire fighting shafts?

[Centurion]

Just wondered what the opinion of "voids" i.e top to bottom "attria" was in protected stairwells or adjacent to fire fighting shafts? These openings run the full five storeys. Premises are residential flats, no need for ff shafts, <18m. No need for lobbies but these have them. I guess Ill get a mixed bag of results from this one. Obviously no sprinkler protection just good old 1 hour compartmentation between apartments.

[kurnal]

If its within a protected shaft and any penetrations are sealed no problem

[CivvyFSO]

It is hard to envisage exactly what you mean, but...

IN protected stairwells shouldn't be a problem. Depends where it comes from though.

The atria may be the reason for the lobbies. Lobbies are there to keep smoke out of the stair, so if you have some atria assisting smoke spread upwards then lobbies may have been added due to this. The whole venting set up may make a big difference to opinions, so it may be prudent to explain that.

Also you say it is a firefighting shaft, is there a dry riser in it?

[Centurion]

NB/    I cant give my opinion here as my colleague has his opinion and is following the thread.

Block 1; we have three staircases the central one being a firefighting shaft including dry riser, lift and lobby (inc smoke control), this one leads to each floor level and every corridor at this level has a fire stopped void in the communial areas adjacent to the lobby. The communial area is again seperated to each corridor leading to compartments, their alternative escape is provided at each end.

One of the protected stairs has a void running internal to the staircase(fire stopped), no lobbying on this occassion (flats/ doesnt need it) and smoke control is afforded in the first adjacent corridor. Second protected staircase, no lobby and smoke control in adjacent lobby.

The second block has two protected staircases without lobbys, Staircase 1 has the void running through it, fire stopped and adjacent corridor has smoke control.

staircase two is the one with the attria in the communal areas adjacent to the head of the stairs...no lobby and in this case the communal area itself could be classed as the adjacent corridor..however the corridor leading to apartments is also adjacent and does have smoke control.

If we are keeping our staircases free from air pollutants would this void from which the inlet air would be drawn hamper our escape? Remembering we have only one fire at a time in the building and the inlet air would only be drawn through the door if the fire were on the opposing side of the attria. If the fire were to be in the communial area it should be so small due to little or no fire loading. We still have an alternative MoE, and at worst the void creates the same hazard as a non fire fightinglift?

Think I may be showing my favouritism here so await some non biased comments.

Thanks by the way as talking all tech with no plans is very hard and I appreciate your tolerance.

[CivvyFSO]

Where you are talking about a void in the stair I can't see a problem, depending on what the void connects to/from and what goes through it. The stair itself is a vertical void, so another void within the void cannot harm, so long as it isn't something daft like the vent from the plant room.

I think the key to this will be whether the required compartmentation has been kept/adhered to. Regardless of having reasonable MoE the fire should not be able to spread up to the next floor. I think atria take on so many forms, and there are so many solutions that seeing a plan/sketch would be the only way to be able to make an accurate comment.

There is a para in ADB about services etc in protected lobbies/stairs. I can dig it out for you tomorrow if that is needed.