Sound insulation question

BigGeorge

Looking to reduce sound transmission for our new PH build & have been given the following choices. Any experience or opinions on these or alteratives would be much appreciated

Ceiling to ground floor - 2 options
- 22mm T&G OSB3, I joists, 200mm rockwool, battens, plaster
- Screed OSB, joists, 100mm insulation, plaster

Internal walls - 4 options
- plasterboard, OSB 10mm, 95mm stud at 600mm centres, 100mm rockwool, OSB 10mm & plasterboard
- option to replace OSB/ plasterboard with fermacell
- plasterboard, 95mm stud , 100mm acoustic insulation & plasterboard
- option to place plasterboard above with Sasmox board

soldsold

For the ceiling and walls the best advice for soundproofing is simply "dont recreate the wheel".

There are tried and tested mixes of joists/ stud walls/ plasterboard, etc etc that work, and tried and tested mixes that dont.

If you try to create a new one, chances are that you will put extra cost in for zero return.

For a cheap soundproof wall, use a staggered stud wall with timber studs, plasterboard, glass wool. All cheap. OSB prices have risen a lot lately, fermacell/ sasmox are expensive (but admittedly they dont need any plaster skim coat of done right).

So build a staggered stud wall using a 6 inch sole plate, 3 inch studs staggered at 600 centres, and single or preferably double skin plasterboard on each side. fill with rockwool or glass wool insulation.

For a better wall, build two 4 inch stud walls side by side at 600 centres, with a 2 inch air gap between them (of course takes up more space than a staggered stud wall). slab the two sides of the walls but definitely dont put plasterboard in the centre if the walls as it reduces the walls effectiveness as it creates a drum effect.

Staple rockwool flexi or glass wool to the top plate, let hang down ans staple to the soleplate.

For the ceilings use a tested ceiling structure from somewhere like soundproofing.com or search google for "ceiling STC".

Definitely trying to make up your own structure will lead to poor results

dan_d

Op, I'm working in a building where sound is important.

As said before, don't reinvent the wheel.Most of our walls are simply 1 or 2 layers of plasterboard both sides with 100mm or 50mm thick insulation. Works a treat. The bigger the cavity, the better the sound rating.

We do however have double walls, with plasterboard in the middle - although I know soldsold advises against that. There's a 25mm gap between the 2 walls, and they achieve about 60dB and more in tests, so they do work...the only disadvantage from your point of view is that your walls would be very thick and you'd lose floor space. Our build up here in those types of wall creates a wall that's up to 400mm thick in total.

BigGeorge

Great responses - put me on the right track.
Looks like double slabbing on either side of 95mm stud with glasswool will give 46dB which is spot on

thanks again

dan_d

No problem....that 46dB result sounds about right, when comparing your wall construction to what we're doing here at the moment and the results we get.Should work out fine for you.

homewardbound11

Dan_D
I have 9mm osb on both sides of a 90 mm stud with a single layer of plasterboard. Is there anywhere you can find this information for sound proofing. Incidently i went for the osb for racking strength.
thanks

dan_d wrote: »

Op, I'm working in a building where sound is important.

As said before, don't reinvent the wheel.Most of our walls are simply 1 or 2 layers of plasterboard both sides with 100mm or 50mm thick insulation. Works a treat. The bigger the cavity, the better the sound rating.

We do however have double walls, with plasterboard in the middle - although I know soldsold advises against that. There's a 25mm gap between the 2 walls, and they achieve about 60dB and more in tests, so they do work...the only disadvantage from your point of view is that your walls would be very thick and you'd lose floor space. Our build up here in those types of wall creates a wall that's up to 400mm thick in total.

ricman

what is osb ?

dan_d

OSB - oriented strand board (thanks, Google!!!)

To be honest, I don't have any previous experience of OSB. I presume when you say racking strength, you mean you're going to be hanging stuff from the wall and you're reinforcing it?? Is that correct?

2 9mm boards (based on what we have here) probably won't achieve much, but with the OSB, it might be improved. Do you have insulation in the middle?

For the plasterboard info - gyproc's website has a lot of information about their products. I believe they have what they call the "white book", which is a manual you can get that tells you all the different types of wall make ups that can be achieved, and the acoustic rating they give. (Am I allowed post their name like that, mods?). Their website also has sections with that info. Failing that, a quick phonecall to them is usually good, they tend to be quite helpful.

I'm not an expert in the subject, but it has been a large part of my life of late due to the job I'm involved in....learning through experience!!Hope that helps.

morning delight

BigGeorge wrote: »

Great responses - put me on the right track.
Looks like double slabbing on either side of 95mm stud with glasswool will give 46dB which is spot on

thanks again

How does this work out cost wise? at 46dB it gives the same soundproofing as a 100mm block wall plastered on both sides.

reefray

Ceiling to ground floor - 2 options
- 22mm T&G OSB3, I joists, 200mm rockwool, battens, plaster
- Screed OSB, joists, 100mm insulation, plaster

BigG

If you go with your first option there will always be some level of impact and general sound transmittance through the OSB to the I-joists and down through the battens to the rooms downstairs. There is another option here that I think you could consider without going the screed route.

If you place 30 or 40mm Rockfloor insulation on your T&G OSB followed by either 15mm Soundbloc plasterboard or 19mm Plank plasterboard you will attenuate the sound before it reaches the wooden elements enabling you to use less Rockwool in the cavity.

This is the buildup I will use on our timber frame build and it is a combination of manufacturers products. If you contact Gypsum Ireland, Lafarge or Knauf tech services and let them know your current spec, what you are trying to achieve and they will give you their own spec on this. Then you just buy on price!

Ray