Sound insulation between floor joists

[garyo]

I've stated on my full plans submission that I'll put 100mm of sound insulation between the floor joists to separate the ground floor dining room with first floor bedroom.

Is there a particular product I should use to comply with regs - does it need to specifically be acoustic insulation or will cavity bats, loft rockwool etc do the job?

Also, it's a 200mm deep floor, so I presume I'll ask the electrician to route cables through holes made in the centre of the joists allowing the insulation to be beneath the cables, sitting on the plasterboard?

Thanks

Gary

 

[Deluks]

100mm rockwool will be cheap and effective. If you aren't putting carpet upstairs then it probably won't make a lot of difference.

 

[garyo]

Thanks. Upstairs will have carpet and underlay, on top of 22mm tongue and groove chipboard. Will the rockwool still make a difference?

Gary

 

[theoldun]

Will the rockwool still make a difference?

Gary

Gary, this is not our best subject. To comply with Document E you only require resistance to air borne sound transmission of 45db. In your situation you are not required to comply with impact sound resistance of 62db or flanking sound.
We comply on our housing with eco joists, 22mm TG chipboard and 15 mm plasterboard and no fibre glass.
How ever as we expect that you will be using solid joists you require a min density of 25kg/m2 to comply with document E
22mm chipboard = 14.5kg/m2, 12.5mm plasterboard = 5.5kg/m2 and 100mm high density rockwall or fibreglass with a density of 60kg/m3 will give you approx 6kg/m2.
We only use 15mm plasterboard these days which will give you 9.8kg/m2 or 12.5 sound bloc which gives 10.6kg/m2 or 15mm soudbloc which will give you 12.6kg/m2.
There are other ways to comply but this is the cheapest and easiest.
If for your own sake you wish to part meet impact sound, then lay acoustic matting under carpet.
By the by, you are not right on your binders. Will try and pick that post up for you this weekend. If you want to know the easy way that we do our joists and floors let us know.
Regards oldun.

 

[garyo]

Thanks Oldun,

The main reason for my concern is to stop noise from the TV below disturbing people who might be sleeping above, so I'll fit the rockwool and some decent carpet underlay.

Re: my roof, in the end I decided to go for a cut roof and after some to'ing and fro'ing with the structural engineer, the BCO seems to be happy with it. I'll get some updated drawings up so you can cast your eye over them.

Cheers

Gary