Bedroom Floor with MLV, Felt & Crumb rubber padding

[Steviemoo]

Hi

UK resident here, first posting. My apartment is one of 4 in a large residential property which was converted in the 70's (before the strict sound regulations came into play). My bedroom is above a large living area below where there is lots of TV, music and particularly conversation noise. They easily possess the loudest voices humanity has yet produced. It's a timber floor and it already has some rockwool between the joists. I caulked all the gaps between the floorboards, caulked all other gaps and around the room, and taped over them. Then I put down a thin layer of laminate underlayment, 2 layers of MLV, caulked and taped, then layed down a combination crumb rubber/felt padding, then the carpet. To my utter dismay, although the TV noise is substantially less, the conversation noise is still ridiculously loud and I'm considering killing them. I get the feeling that just adding more MLV won't do the job. Can anyone suggest what I can do? I think a floating floor is out of question as I suspect the floor won't support it.

[Randy S]

The reason you have not had a better reduction in sound is because you have placed the system down incorrectly. What you need to do is place a 1/4" or 1/2" layer of padding underneath the MLV barrier. This will decouple the Barrier from the hard surface and allow it to perform as a sound Barrier... when MLV is flat on a hard surface it will not perform to its full potential. Make sure you tape the seams of your plywood with metal tape,be sure you offset the seams of each layer of MLV and metal tape all seams. The layer system you should have is  padding/MLV/MLV/padding/carpet. Also Jute padding is not good for sound you should use Rebond carpet padding.

[johnbergstromslc]

Hi

UK resident here, first posting. My apartment is one of 4 in a large residential property which was converted in the 70's (before the strict sound regulations came into play). My bedroom is above a large living area below where there is lots of TV, music and particularly conversation noise. They easily possess the loudest voices humanity has yet produced. It's a timber floor and it already has some rockwool between the joists. I caulked all the gaps between the floorboards, caulked all other gaps and around the room, and taped over them. Then I put down a thin layer of laminate underlayment, 2 layers of MLV, caulked and taped, then layed down a combination crumb rubber/felt padding, then the carpet. To my utter dismay, although the TV noise is substantially less, the conversation noise is still ridiculously loud and I'm considering killing them. I get the feeling that just adding more MLV won't do the job. Can anyone suggest what I can do? I think a floating floor is out of question as I suspect the floor won't support it.

Also, a floating floor need not be concrete.  You can build a floating floor with 2 layers of plywood/OSB screwed together on top of a soft foam pad.  Not as good as concrete, not by a longshot but better, certainly.

[Steviemoo]

I did put a layer of laminate underlay beneath the MLV but obviously it wasn't enough. Would you go for the floating floor or putting the extra padding down?  And why do you say the rebond is better than the crumb rubber & felt?

[Mark Daveis]

Putting more padding so the mlv is not trapped flat will help a bit but realistically the only way to reduce loud noise like that is to use a floating floor of about 25kg/msq or more.

[Steviemoo]

Ok, I'm now leaning toward installing this stuff: http://www.noisestopsystems.co.uk/Soundproofing_floors/noisedeck_32.htm

Its an 18mm chipboard bonded to triple-layer foam/polymer composite. Will this do the trick? Only thing I'm confused about is that the guy at the company said it was primarily intended for impact noise.

[Steviemoo]

Further to the above: Instead of splashing out on that expensive stuff, I'm thinking of putting a resilient layer on top of the MLV, then 18mm T&G chipboard. Will this have an appreciable effect on the airborne noise?

[Mark Daveis]

You need at least 25 kg mass so its 2 layers of 18 mm chip board/plywood/osb or other.
Its better to hang it as a decoupled ceiling but can be mounted on say helical springs or neoprene as a floor as long as there is 2 or more inches of airspace.
Yes looks like impact noise reduction unless you have problems with that and expensive too so I would in most cases make my own.

[Steviemoo]

2 layers of 18mm chipboard (plus padding and carpet) is a hell of an increase in floor height. Would one 18mm layer on top of a resilient layer just not be worth it? What material is best, chipboard or plywood?

[Mark Daveis]

Chipboard is a bit better as the material is shredded so less resonance.
Use something like 12 mm ply and 3 layers of mlv on top which is only about 18 mm and using just 18 mm of wood board will give much less than the 20 kg minimum of mass. This will still work but not well if the noise is quite loud so I would recommend at least 20 kg unit mass unless the problem is not that bad. Also you need to raise all this mass at least 2 inches for max effect so this also raises the floor height.

[Steviemoo]

It's the raising of the floor height that concerns me - 18mm worth of wood, plus the MLV (all of which you say needs to come up by 2 inches), plus the padding, plus the carpet. I want to be able to get into the room without using a ladder. I just thought that the MLV plus a plywood floated floor would surely make a big difference, but it sounds as though it won't, which is a bit dispiriting! 

[Randy S]

You have a height issue, just decouple the MLV with a thicker pad and seal everything seam you possibly can before you layout the material. I understand the Mass law but you can only achieve the so much based on floor height. Either float the floor or make the underlayment system it will be better than what you have now. Also Rebond is a combination of foams that help aborb noise and impact better.

[Steviemoo]

Ok, so the options I'm thinking of are:

1) Put down a layer of padding, 2 layers of MLV, more padding, then carpet (as suggested above)
2) Keep the existing MLV, then a resilient layer, and a layer of 12mm ply or OSB, then padding and carpet.

Which method is going to give me the best performance in terms of airborne sound reduction?

I'm also now considering doing the rest of the apartment. I can't be taking up any floorboards or farting about in between the joists (besides the noise elsewhere is pretty negligible compared to the bedroom), so would the best option for airborne be to install MLV as described above or just go straight for the floating floor option?

[Randy S]

For Airborne noise just do the MLV system...
No matter which system you do you still have to correct the error. If you keep the MLV the way it is now you will gain very little from the MLV.
Also remember to caulk around the entire perimeter of the room on MLV Layer after the tack strips are placed.

[Steviemoo]

Incidentally the tack strips have just been fitted through the MLV. Bad thing? If so, how do you get around that? If they're placed around the perimeter and the MLV butted up to them, does that not mean the area they sit on isn't soundproofed?