# Why didn't i put in hollow core floors??



## Mayo2008 (11 Jan 2010)

We build in 2008 and decided to put in timber joists rather then hollow core floors (fyi house approx 2800) because of the add'l cost but now really wish we did.  Is there anything we can do now to reduce the noise of people moving around upstairs (even in rooms with carpet you can hear even movement)?  Would appreciate any advice ye have  
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## RKQ (11 Jan 2010)

Layers!
There are many ways to soundproof timber joist floors, especially during construction. 

Building up layers of material is the best approach -ie ply on joists with insulating foam / rubber/  then floating floor, double slab ceiling with staggered joints and 100mm thick Rockwool flexi between joists.

There are a number of products- Rockwool insulation, recycled tire matting, 19mm Gypsom plank laid on tophats between joists.

Check out products on Google.


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## onq (11 Jan 2010)

RKQ said:


> Layers!
> There are many ways to soundproof timber joist floors, especially during construction.
> 
> Building up layers of material is the best approach -ie ply on joists with insulating foam / rubber/  then floating floor, double slab ceiling with staggered joints and 100mm thick Rockwool flexi between joists.
> ...



+1 what RKQ said.

Mass is a great absorber of sound, but you can go the lightweight route too.
A floating floor and acoustic tiles can absorb impact and airborne noise.
What you cannot disguise easily is the noise of the joists themselves.

Sometimes the joists can be marginally sized, or poorly restrained laterally - side to side.
If the joists are adequately sized you can stiffen them when you're installing the floating floor.
If they aren't well sized you could drop in additional joists I suppose, although that's a lot more work.

You can also install sound absorbing material suspended on matting draped between the joists.
The matting is fixed to the top of the joists to prevent the weight of the fill popping the ceiling below.
The fill will tend to add weight so you should get an engineer to check the load carrying capacity of the floor.
The other issue is the detailing of the studs themselves - filling with Rockwool and double slabbing will improve matters.

This is costly and after-the-fact - the transmission paths for noise should be considered in relation to the house as a whole not piecemeal.
It would be useful to consult some who actually does this for a living or else retain someone to contact them on your behalf and discuss details.

HTH

ONQ.

[broken link removed]


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## suzie (12 Jan 2010)

In a similar position, wish I know was told of the resulting noise. Can anybody recommend a suitable expert to rectify the situation?

Thanks

S.


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