Hopefully someone can point me in the right direction to obtain the correct info. I'm currently in discussions with a building contractor about the number of exits required in a CAT 3 lab. I'm of the opinion there should be two exits, the building contractors says not. Any guidance other than building regs? Thanks Andy

Thank you. Any idea if there is a British Standard? Fire regs say Ideally have two exits.

Thanks Pete. Its as I thought really. Its Biological so will come under CoSHH. Just cant find anything other than the building regs which say Section b1.v there should be alternative means of escape. At the moment the plan is to build the cat 3 lab with one exit and no other means of escape. My argument is there should be an alternative means of escape. The other point is the lab will be in a basement with only one way in and out of the basement. I don't want to sign this off without getting the alternative escape route.

Why the objection to a single travel distance? Unless the lab is working using materials which may develop a rapid spread of fire, I am not sure what the issue is? I think we used ADB in ours, but the work carried on is low fire risk. I have also seen the sealed escape doors (in this case, 600mm x 600mm escape hatches under benches!) that A Kurdziel talks about in a lab built in the last few years. We installed aspirating SD in the rooms and in the air gap around the rooms for early detection, and had MCPs installed in all labs so that staff could operate them quickly without going through air locks It was the air locks that posed the biggest issues. Building control made a fuss as they said they formed inner/inner/inner rooms, whilst I argued they were lobbies. Plus the MOE through the air locks did slow down the MOE as staff had to pass through them unless conditions in the space were untenable. I am still not 100% happy with the set up, but unannounced fire drills show that they work!

Unfortunately my experience was with a low/non combustible process, so perhaps not comparable with this trickier one Your layout of course is an inner/inner room which so often freaks out building control and fire safety folk alike. However, I try not to get myself too excited about this concept. The travel distance through each room, plus the nature of activity in those access rooms is critical when assessing this risk. EG: If there's a long travel distance through an access room where flammable substances are being stored or used, you have a problem The coverage of AFD and type of heads are critical to achieve an early detection of fire, and the door fixings from the high risk area may need to be panic bolts/pads to help with a rapid movement. Lastly the management of the housekeeping in the access rooms and circulation space needs to be controlled to avoid combustibles and ignition sources Can you help fill in any of those details? (although I am doubtful I can give anywhere near a definitive answer to your questions being blind as it were)

We have 2 cat 3 rooms on 2 sites, Both are single travel, less than 9 meters with a fume cupboard at the bottom one comes into a lab with 2 way travel, the other exits into acorridor with 2 way travel, both have in date certification and built to standard. You do not need 2 way into such a small room negative air pressure is more important