Ceiling cavity fill with insulation.

bauderline

Folks,

I have a ceiling which consists of precast slab and plasterboard attached using the gypsum system with a void of about 100mm. I am toying with the idea of pumping this with some sort of insulation. Is this a good idea or a bad idea ? What sort of insulation could I use in this instance ?

P.

bauderline

Anyone any thoughts on this ?

gman2k

This is the void above your suspended ceiling and beneath your concrete slab?
You don't need any insulation for sound purposes, as the concrete slab is looking after that for you.

Insulations that can be pumped in however are the likes of blown fibre glass, blown Rockwool and cellulose.
However, in your instance, how would you pump them in, as you have plasterboard below and conc. above? these insulations are best pumped in from above in timber floor applications, where you could uncover the joists by removing strips of flooring.

bauderline

Hi Gman,

There are some drain pipes running under the slabs and I want to further minimise any sounds from these. I don't have joists as the ceiling is suspended using the gypsum system which is sort of a metal framework. I was hoping a few holes could be drilled in the ceiling and the insulation could be pumped in that way as there is nothing to prohibit it expaning across the void... if you get my drift....

I suppose I should talk to the professionals, just toying with the idea at the moment.

P.

RKQ

You could consider wrapping the pipes in Rockwool /fibre glass, if you still have access to them. But if the ceiling is slabbed, then I'd say its too late to insulate.

Even if you could "blow-in" bead or celleose, I'm not sure either material offers certified sound insulation values. You'd also have to be careful not to over-insulate electric cables.

gman2k

RKQ wrote: »

You could consider wrapping the pipes in Rockwool /fibre glass, if you still have access to them. But if the ceiling is slabbed, then I'd say its too late to insulate.

Even if you could "blow-in" bead or celleose, I'm not sure either material offers certified sound insulation values. You'd also have to be careful not to over-insulate electric cables.

Never blow in bead, as they react with the pvc of elec cables.

Cellulose would be a good sound insulator, as it has a high density.
Drilling small holes and pumping in fibre product is no good either, as the fibre blows with force and can only go perpendicular in this method - hitting the slab over and soon blocking the hole.
Long cut strips is best for pumping in fibre to a cavity such as this - and from above!

As RKQ says, wrapping the drainage in rockwool would be the best solution here if the ceiling is not slabbed.