Mr Blobby Posted July 4 Share Posted July 4 (edited) The architect details on our block cavity passive build include a gypsum casoline MF suspended ceiling under the hollow core slab. Our builder wants to use timber instead of metal casoline to construct the 200mm ceiling void. Our builder says timber is more solid than a metal suspended ceililng. Reading the posts on here it looks like the metal casoline type is easier to get level. I don't see much evidence on here of timber construction for the ceiling void/suspended ceiling. Which ceiling void construction is best and why? Timber or metal? Edited July 4 by Mr Blobby Link to comment Share on other sites More sharing options...
Conor Posted July 4 Share Posted July 4 No no no no no. Stick to the metal. It goes up so fast, perfectly level and straight, little wastage, great sound insulating properties. 2 1 Link to comment Share on other sites More sharing options...
Iceverge Posted July 4 Share Posted July 4 (edited) Metal is incredibly fast. 2 men did 90m2 for us in about 4hrs and it was perfectly level. We varied the ceiling void from 300mm to just about enough to fit the 75mm MVHR pipes in different rooms to maximise ceiling height. The only place I would consider timber is with 22x70mm strapping where there was no ducting, again to maximise the ceiling height. However you'd need a lots of shimming to get it level as the hollowcore slabs have a curve on the bottom. Edited July 4 by Iceverge 1 1 Link to comment Share on other sites More sharing options...
Mr Blobby Posted July 4 Author Share Posted July 4 The cynic inside me suspects our builder had joiners lined up. Looks like metal is the way to go. Link to comment Share on other sites More sharing options...
saveasteading Posted July 5 Share Posted July 5 It's like all the suspended ceilings in every modern office. Nobody would consider timber. Quicker, cheaper, adjustable. You also have a nice void for cables. But the hangers should be simply dropped between the slabs before concrete or screed goes over it. 1 Link to comment Share on other sites More sharing options...
Iceverge Posted July 5 Share Posted July 5 3 hours ago, saveasteading said: But the hangers should be simply dropped between the slabs before concrete or screed goes over it. They just shot nailed the hangers in in our house with a Hilti gun. 1 Link to comment Share on other sites More sharing options...
Mr Blobby Posted July 5 Author Share Posted July 5 (edited) 14 hours ago, Conor said: great sound insulating properties Do I need to worry about sound through a hollow core slab? I had hoped that the density in the slab would be a pretty good sound insulator. If not then what additional sound insulation should be installed in the void, some rockwool, or something else? 4 hours ago, saveasteading said: But the hangers should be simply dropped between the slabs before concrete or screed goes over it. That's interesting. Our gaps have been sealed with dry concrete a long time ago. Edited July 5 by Mr Blobby Link to comment Share on other sites More sharing options...
saveasteading Posted July 5 Share Posted July 5 1 minute ago, Mr Blobby said: sound through a hollow core slab? What is on top of the slabs? What stage are you at? Acceptable noise levels depend on room purposes. What is above and below? Link to comment Share on other sites More sharing options...
Mr Blobby Posted July 5 Author Share Posted July 5 (edited) 17 minutes ago, saveasteading said: What is on top of the slabs? What stage are you at? Acceptable noise levels depend on room purposes. What is above and below? Good question. On top of the hollowcore slab (ie the first floor covering) will be 10cm screed. That may be 5cm insulated screed and 5cm standard screed. The insulated screed was originally intended to make fixing of ufh pipes on first floor easier but we binned the upstairs ufh so no reason to have the insulated screed now. Unless of course it reduces sound transmission. Screed not pured yet. First fix plumbing is in. Roof on, most windows in, we are a whisker away from completely watertight. On top of the screed will be mostly tile/wood, not much carpet, although wife may overule me on this. Above the kitchen will be tiled bathroom so the noise transmission here is the key. I guess some rockwool in the void here would make sense, or is there some bespoke gypsum casoline product? Edited July 5 by Mr Blobby Link to comment Share on other sites More sharing options...
saveasteading Posted July 5 Share Posted July 5 OK. So if you stamp on the floor now, you will hear it below. With another 5cm of screed it won't reduce much. But the density will stop nearly all background noise in both directions. The ceiling will help a lot. If it is , for example, living room below and bedroom above it is probably OK. For total silence you add soft stuff either above or below. Eg in schools it depends what classes are there. Woodwork next to maths is a bad idea but it can be done. Link to comment Share on other sites More sharing options...
Alan Ambrose Posted July 5 Share Posted July 5 >>> Woodwork next to maths is a bad idea Can't put the nerds next to the crafty kids? >>> wife may overrule me on this No appeals procedure in your house? Link to comment Share on other sites More sharing options...
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