Hi we need to put up a new ceiling the first floor is a shop/cafe and above is a flat. we are planning to put rockwool slabs inbetween the joists for sound and insulation then on top we were going to do one layer sound board and one layer fire board - is this the best approach or should we just do 2 layer fire board with the rockwool, or would one layer fireboard be ok?? Please help , as very confused!
Hi DIY What fire rating are you trying to achieve? 1 or 2 hours? 12.5mm fire board can provide about 1 hour of rating, a standard 12.5mm board can provide 1/2 hour fire resistance. So you will need at least a double layer of some description. I do not believe that the rockwool slab infill will be allowable as part of you fire resistant calculations because any gaps between the sides and the joist will be as if the slab is not there. I would have thought that in your situation you will need two hours of separation and therefore you will have to double board with fireboard. PLease check this out with building control As for sound, make sure that the slabs fit tight between the beams (no gaps) any gaps and sound will pass through them as if you had never put it down in the first place. The double board will also help. Accoustic performance is best achieved with a DENSE closed cell material (ordinary fibreglass rolls will provide some accoustic benefit but no where near as much as say 100mm cellotex rigid board, or for example, the best sound insulation would be achieved by concrete slab!) Finally are you more interestead in the noise coming down from above or noise going up from below? Hope this helpes Russ http://www.iiplumbing-services-derby.co.uk
Hi diydisaster As a mater of interest are you going through building control ot just putting a new celiling up and want to play safe? I asked this as I want to rent the flat above my shop but also would like to fireline it but do not want to go the extreme my friend is having to do through building control. The reason he has to go via building regs is because he is changing it from a office to residential. You would not believe the amount od work they want. Every wall that has a external face has to have special insulation boards fitted to them. all other walls and party walls have to have fireboards fitted to them. The floors have to have a special soundproofed floating floor system over them. The ceilings below have to have to be boarded with fireboards etc. the list goes on. I reckon it's about £5000 per room before even starting anything else.
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