Sound insulation for concrete slab first floor

[Gaf]

I recently posted about stud wall sound insulation and wanted to keep things separate.

 

We're getting concrete slab first floor put into new build. Going through construction drawings, and there's no particular sound proofing insulation on the drawings (as best I can tell). The layers are:

• 75mm screed for underfloor heating
• 25mm heat insulation (Kingspan therfloor TF70)
• Precast concrete slab (no thickness specified, only shop drawings to be submitted by builder for approval)
• 185mm service void
• Battens
• 12.5mm Suspended plasterboard, skim finish

 

Wondering should this include some additional sound proofing? Would SoundBloc plasterboard be sufficient?

 

This is our permanent home and we'll have two kids growing up in this house (have an 18 month old and another on the way), so we want to get this right.

[Nick Laslett]

My brother had this configuration in his build. I would be surprised if you have any problems with sound transfer. We filled our service cavity with Isover fibre glass wool, this should reduce the drum effect of sound resonances. 
 

Like with the wall buildup, you can use the decoupling clips for the suspended ceiling to decouple from 1st floor. But the UFH insulation is already a decoupling layer, so this might be overkill. 
 

Always very frustrating with these decisions, as you only get one chance to do it right and you never know if you’ve done enough to satisfy your design goals. 
 

Have you thought about pre-cast concrete stairs, or poured in situ concrete stairs?

 

Also, standard UK doors are not very acoustically sound. You can get Euro style interior doors that have rubber gaskets for much better soundproofing. 

[Gaf]

@Nick Laslett We have family who have done an identical build to our proposed one and they say the sound proofing is excellent (though they don't have little kiddos so only their own TV noise to work from).

 

Funnily enough the architect has put in a pre-cast concrete stairs (even though we specified timber). Am I right that the concrete in particular is an additionally good sound proofing way to go?

 

Good to know about the doors! We're in the rep of ireland, so not sure what ours are like but I'll check that.

[Conor]

The concrete slab and suspended ceiling is more than enough to pass the BCAR sound transmission requirements. We put in 50mm mineral wool as well, just to be sure. All good.

 

I'm assuming your suspended ceiling will be a metal system? 

 

Fyi unless you've massive spans you'll be using 150mm precast slabs. 

 

Oh, instead of the 25mm insulation and 75mm screed, consider 50mm TLA, UFH, then 50mm liquid. Far faster job.

[Iceverge]

Carpet, underlay. 75mm concrete screed. 150mm hollocore concrete planks. 100mm ish dropped MF ceiling. 12.5mm plasterboard and skim. Zero air paths between rooms. 

 

Dead quiet. 

 

I can occasionally hear the dishwasher at night. My wife can't but I'm convinced that's coming up the eps beads on the cavity from window to window.