1st floor

Stev3

Hi I have trawled through the net looking for an answer to the following question. I Have a timber first floor and I want to try to eliminate as much sound as possible. for my first floor I will have the following: 9 by 2 C 16 timber joists at 300mm c/c osb 3 flooring with 100mm rock wool. A liquid light weight concrete screed of 50mm is poured over this.My main issue is sound. Obviously it is too late to put in a precast floor and also I cannot increase the weight of the liquid screed as the structure won't support this so I am looking for other viable options. Any advice appreciated.

BarneyMc

If you're putting in laminate flooring upstairs then you could use an acoustic underlay. It might help.

mike_2009

I'm looking at a particular solution for my timber framed first floor (new build). I'll pm you details. I'm not sure about concrete screed compatibility however but it might send you in the right direction.....

Stev3

Thanks yes will be putting in laminate floor. I live in a house at the moment with just a timber first floor - will the screed help any bit with sound as I had this argument with the builder and I was assured it would be a concrete first floor but it is not. The house I live in at the moment is so noisy- it's an old house though!

mike_2009

The main problem with old floor joists is they creak! You need to have the floorboards taken up the shims put in where required to remove this issue. Then the soundproofing material I sent you should help quite a bit more. The builder should be able to resolve the creaking issue as it's just old joists that have warped / shrunk over time or were never put in well in the first place.
I'm sure there are other approaches but have a chat with your builder for their best advice. I wouldn't like to lay concrete on top of an existing problem and there's the issue of weight, not something I can advise on unfortunately.

BryanF

Stev3 wrote: »

Thanks yes will be putting in laminate floor. I live in a house at the moment with just a timber first floor - will the screed help any bit with sound as I had this argument with the builder and I was assured it would be a concrete first floor but it is not. The house I live in at the moment is so noisy- it's an old house though!

What ?

Who is the contract administrator, who is the structural engineer and what do the drawings state?

Stev3

The contract states 50 MM. light weight concrete screed. It is my own fault - I did not understand the difference between a precast slab and the above. However I did ask my architect who is overseeing all the worK with an engineer he works with was my first floor concrete- he had the same contract I had as I sent it on to him and he said yes and he said that the appropriate foundations were included on the bottom floor to support this. Builder said same. What annoys me is I asked this question 4 times between the builder and architect. (Lesson learnt never trust anyone unless you understand fully yourself)

Now I am wondering does anyone consider a 50mm light weight concrete screed concrete in the industry or what there a mistake made on my house. I also had to pay 6k extra for this- I am in a rural location and I have a friend building and her precast slab is costing heR the same and she is getting a proper floor so now I am thinking wtf so any thoughts on the above would be appreciated. I know there is nothing I can do about it now.

cork2

OP I don't blame you for being annoyed with your architect and builder. Whereever the blame lies may be irrelevant at this stage.

What I will say is that your timber floor with lightweight screed is actually a very good system. I've just joisted out a house for the same system. This will be my 7th time doing it. If it was my house I'd go for this system over a precast slab. Timber is a much easier product to work with than concrete.
As for the sound issue, the lightweight screed really deadens the sound. In a few cases I've seen them spray the underside of the floor with spray foam, this completely deadens any sound from above but whether this is a good idea or not is a separate arguement.

fits

Interested in this also. Husband is very interested in pre cast concrete, I am interested in looking at other options. Our budget is tight.

Stev3

I feel better knowing that people do use this system. Yeah I am hoping it deadens the sound by a good bit as the house I rent is awful noisy but I think there is just something wrong with the joists.

mfceiling

I've never seen a timber floor deaden sound better than precast.

Worked on a renovation a while back and the guy had joists, rubber strips on the joists, and 2 layers of ply. Then he put 100 mm insulation in the void and 2 layers of gypsum soundboard under that. You could still hear the lads upstairs walking around.

Maybe with underlay, carpet and the house ready to live in it might be slightly different.

My mate lives in a house with precast floors and when my kids play upstairs with his you can't hear a jot downstairs... (mind you that is also a pain having to run up and down to make sure they haven't wrecked the place!!).

murphaph

We have timber first floor with osb, rock wool between joists, UFH in first floor with sound insulation beneath it and sand cement screed on top and sound is not a problem at all. We have a concrete slab between ground floor and basement and I honestly haven't noticed any difference in sound transmission between floors, though I'm sure if it was tested scientifically the concrete would come out on top.

Make absolutely sure the screed truly floats and is isolated from other building components. If your skirting "binds" the floor to the walls then vibrations will be transmitted into those walls and around the house. When tiling, make sure no adhesive or grout binds the floor to the wall. Make absolutely sure a perimeter sound insulating barrier is installed around your screed. I think it's called an isolating strip in English.

Stev3

Thanks murph! Just when you say if your skirting binds the floor to the wall what do you mean? I haven't got the skirting done so I want to make sure they do it right.

murphaph

Stev3 wrote: »

Thanks murph! Just when you say if your skirting binds the floor to the wall what do you mean? I haven't got the skirting done so I want to make sure they do it right.

I just mean....you have presumably a floating screed which is isolated from the walls with a strip of foam insulation about 10mm thick. You don't want to now bypass that isolating strip by fixing skirtings tight to the floor as sound will transmit into the walls from the floor.

You should mind the detail here to ensure there's a gap between the bottom of the skirtings and the floor which can be sealed with silicone.