[FunkyMunkey]

Hi,

I'm just about to start building stud walls in the alcoves of the existing party wall, for the purposed of sound insulation.

For a variety of reasons - such as wanting to lose as little room space as possible while making sure the wall is sturdy - I've decided on 75mm insulation rather than 100mm or 50mm.

Would Wickes 75mm Cavity Wall Insulation be OK? The insulation itself looks almost identical to their 50mm General Purpose Insulation, and the only difference i can see on the packet is that the 75mm stuff is waterproof.

Thanks in advance for your help!

[FunkyMunkey]

Any thoughts?

[Ross007]

I am currently in the process on renovating my whole house. So I had the opportunity to soundproof all party walls inc the bedrooms. I used the Wickes stuff it seemed nice and thick. I also wacked on 2 sheets of 12.5mm plasterboard.

I can't tell you how good it works yet as I am not living in the house yet!!

[FunkyMunkey]

Ok, I've started building the wall, but have a few questions:

1) It is being built on a suspended wood floor, which has a gap of about 2ft between the floorboards and the ground. Do you think it'd be worth sticking some loft insulation rolls in the alcove's underfloor to stop transmission under the floor?

2) The frame for the new wall is 28mm in front of the party wall (28mm gap + 47mm wood = 75mm). While I'm obviously going to stick insulation between the studs, should I also cut some thin strips of insuation to go behind the studs and sole and head plates (i.e. between them and the existing wall).

3) When I put the plasterboard on, should I try to minimze the gap between that and the floor (10mm-ish)?

4) Should I try to overlap the edges of the two layers of plasterboard?

5) I'm going to use Green Glue between the layers of plasterboard. It sounds a bit strange, but as I'm just going to sand and stain the wood floor, would it be worth attaching some Green Glued plasterboard UNDER the floor, between the joists. Would this have a similar effect as, for example, green gluing a plywood subfloor on top of the current floor before laying underlay and laminate flooring (if that makes any sense..!)

Any help would be REALLY appreciated. I don't want to mess this up!

Cheers!

[FunkyMunkey]

[FunkyMunkey]

Someone must have an opinion, shurely!

[Lizard]

Originally Posted by FunkyMunkey

Ok, I've started building the wall, but have a few questions:

1) It is being built on a suspended wood floor, which has a gap of about 2ft between the floorboards and the ground. Do you think it'd be worth sticking some loft insulation rolls in the alcove's underfloor to stop transmission under the floor?

Not really, unless you fit the insulation between the floor beams, otherwise the sound waves can still travel thourgh the floor and out of the walls before they hit the insulation resting on the ground

Originally Posted by FunkyMunkey

2) The frame for the new wall is 28mm in front of the party wall (28mm gap + 47mm wood = 75mm). While I'm obviously going to stick insulation between the studs, should I also cut some thin strips of insuation to go behind the studs and sole and head plates (i.e. between them and the existing wall).

No what you are trying to do is make it as hard as possible for the sound waves to travel through to next door. by putting in strips connecting the two then you are giving a direct path for the sound waves to travel

Originally Posted by FunkyMunkey

3) When I put the plasterboard on, should I try to minimze the gap between that and the floor (10mm-ish)?

Yes, but you will need to fill the gap with a silicon product to remove any air gaps

Originally Posted by FunkyMunkey

4) Should I try to overlap the edges of the two layers of plasterboard?

Yes, otherwise your creating a weakness in the wall for sound to travel through

Originally Posted by FunkyMunkey

5) I'm going to use Green Glue between the layers of plasterboard. It sounds a bit strange, but as I'm just going to sand and stain the wood floor, would it be worth attaching some Green Glued plasterboard UNDER the floor, between the joists. Would this have a similar effect as, for example, green gluing a plywood subfloor on top of the current floor before laying underlay and laminate flooring (if that makes any sense..!)

Unless you put you put green glue (horrible stuff to work with mind ) between the floor boards and the beams, then the sound can pass through directly that way and bipass the plasterboard between the beams

[dar2005]

Laminate Flooring? Solid wood flooring is getting so cheap now, and the quality of the result is SO much better.

[FunkyMunkey]

Originally Posted by dar2005

Laminate Flooring? Solid wood flooring is getting so cheap now, and the quality of the result is SO much better.

I actually meant solid wood flooring, but couldn't be bothered to type it out!

[FunkyMunkey]

Originally Posted by Lizard

Not really, unless you fit the insulation between the floor beams, otherwise the sound waves can still travel thourgh the floor and out of the walls before they hit the insulation resting on the ground

That's what I was thinking: stick some insulation between the joists, maybe even filling up the whole of the underfloor space between the ground and the floorboards to about a metre away from the wall

Originally Posted by Lizard

No what you are trying to do is make it as hard as possible for the sound waves to travel through to next door. by putting in strips connecting the two then you are giving a direct path for the sound waves to travel

I've actually decided to buy the 45kg/m insulation from NoiseStop Systems. On their website, they seem to suggest forming as tight a fit as possible, which is at odds with your suggestion. Although yours does make sense. Do you think I shouldn't glue the insulation to the wall either, as they suggest (although they don't seem to be talking about a stud wall, but rather a wall made sompletely of insulation).

[Lizard]

Originally Posted by FunkyMunkey

That's what I was thinking: stick some insulation between the joists, maybe even filling up the whole of the underfloor space between the ground and the floorboards to about a metre away from the wall

What do you mean up to a metre away from the wall? Put some insulation between the floor beams would certainly help to reduce the noise escaping.

Originally Posted by FunkyMunkey

I've actually decided to buy the 45kg/m insulation from NoiseStop Systems. On their website, they seem to suggest forming as tight a fit as possible, which is at odds with your suggestion. Although yours does make sense. Do you think I shouldn't glue the insulation to the wall either, as they suggest (although they don't seem to be talking about a stud wall, but rather a wall made sompletely of insulation).

What you are trying to do with soundproofing is to make the path of the sound waves as difficalt as possible (to try and completely absord/break them up). The best way to do this is to have an air gap between the two walls and insulation to absord as much as possible. The reason for this is sound travels in two ways ie through air and through materials (ie if you put your ear on a train track you can hear the train coming long before you hear it in the air).

You could have the stud wall empty and then the insulation glued on to the wall, but this way more air sound waves will hit the wall and then travel through via the materials to next door. Far better to have the insulation in the stud wall which then reduced the sizes of the waves that then travel through the air gap and on to the wall and through to next door. Of course the best thing to do (if you have the money/time) is to glue insulation onto the wall, then a air gap, then insulation in your stud wall.

Dont forget though that the same rules apply to your ceiling and floor.

[Lizard]

Originally Posted by FunkyMunkey

I've actually decided to buy the 45kg/m insulation from NoiseStop Systems.

Dont get to hung up on this, when i did my room i used a 100+kg/m (£27 for 50mm by 1m by 3m sheets) and have achived better results with normal 300mm loft insulation (provided its pack tight) on other sound proofing jobs at a fraction of the price.

If possible you should also fit a false ceiling to stop the sound traveling upstairs. Also how old and were is your house in leeds (living here i know most of the old house types quite well) and it will allow me to give help on the floor issue. (rather surpised that you have a house with suspend wooden ground floor with soil underneath in leeds, their usually concrete floors or have basements)

[FunkyMunkey]

Originally Posted by Lizard

What do you mean up to a metre away from the wall? Put some insulation between the floor beams would certainly help to reduce the noise escaping.

In other words, under the floor the area between the wall and 1 metre out from it will be filled with Insulation.

Originally Posted by Lizard

What you are trying to do with soundproofing is to make the path of the sound waves as difficalt as possible (to try and completely absord/break them up).

See, this is what confuses me: by that rationale, shouldn't I fit insulation behind the studs because that will break up the sound waves more? If I just leave a gap between the studs and the wall, they will have a free path to the party wall. I don't have the space to glue the insulation onto the stud wall, so it'll have to be within it.

Originally Posted by Lizard

Dont forget though that the same rules apply to your ceiling and floor.

Yup, I will be sticking some insulation inbetween the joists of the ceiling, too.

Originally Posted by Lizard

Also how old and were is your house in leeds (living here i know most of the old house types quite well) and it will allow me to give help on the floor issue. (rather surpised that you have a house with suspend wooden ground floor with soil underneath in leeds, their usually concrete floors or have basements)

It's a 1930's semi in the Pudsey/Farsley area. half of the ground floor is suspended floors (living room/diner), and the other half is concrete.

[Lizard]

You would live in the one area of leeds i don't know that well!

As for what you are planning to do under the floor sounds good to, As for the ceiling is their no way you could put a false cieling in as it all comes back to an air gap again.

As for the gap in the stud wall and why an air gap is so important all comes back to how sound travels. Now i'm no expert in physics here so bear with me. Sound travels in two ways impact and air, so by having an air gap you are stopping the path of impact sound travelling through to something else.

Also (and this is were i should have been clearer) with air sound when they hit your wall they will be transfered into impact sound that will then travel through the stud wall on to to next door if their is no air gap. With an air gap, the air sound hits your stud wall and is transformed into impact sound which then travels through the insulation/plasterboard until it hits the air gap, when it changes back to air sound, it then travels through the air and hits your seperation wall were it changes back to impact sound and on to next door.

So (providing the above makes sense) by having an air gap you break up and alter the sound waves far more than if you don't.

[FunkyMunkey]

Originally Posted by Lizard

As for what you are planning to do under the floor sounds good to, As for the ceiling is their no way you could put a false cieling in as it all comes back to an air gap again.

I'm afraid money doesn't permit it.

Originally Posted by Lizard

So (providing the above makes sense) by having an air gap you break up and alter the sound waves far more than if you don't.

Thanks.

So does that mean that I shouldn't try to really pack in the insulation between the studs (or glue the insulation to the party wall) because that removes more air gaps: between the plasterboard and the insulation; and the insulation and the party wall.

I think I might cancel the order for the Heavy Density Insulation and just buy some Wickes stuff...

[Lizard]

Hi, i thought the easiest way to explan would be via a drawing. Ideally you want the air gap between the wall and stud wall to be 6 inches if poss.

[FunkyMunkey]

Originally Posted by Lizard

Hi, i thought the easiest way to explan would be via a drawing. Ideally you want the air gap between the wall and stud wall to be 6 inches if poss.

Again, unfortunately that 6 inch gap won't be possible, mainly because I can't afford to lose that much room space.

The studs are 25mm away from the bottom of the party wall, but because the wall is wonky, they are 50 mm away at the top. So if I follow your diagram, but leave only a 25-50mm air gap, it would be the best option, right?

Considering Green Glue is supposed to be good for low frequencies, could I take off the the head plate, green glue a 100mm piece of plasterboard to the ceiling so that its edge is flush with the edge of the stud wall, then re-attach the head plate to that (see attached image). If I did a similar thing at floor level, would this reduce flanking noise? Or am I talking complete balls?!

Also, I will eventually be mounting an LCD on the wall and want to hide the wires. I was planning to run some trunking behind the plasterboard with small between drywall mounting boxes (see second attached image). Is this a no-no in terms of soundproofing, or will the effect be negligible?

Finally the side walls are wonky, too, so there are gaps of up to 1cm between the end studs and the walls they're screwed to. I was thinking of filling the bigger gaps with expanding foam and the smaller gaps with acoustic sealant. Any thoughts on this?

Much appreciated!

[Lizard]

Originally Posted by FunkyMunkey

Again, unfortunately that 6 inch gap won't be possible, mainly because I can't afford to lose that much room space.

The studs are 25mm away from the bottom of the party wall, but because the wall is wonky, they are 50 mm away at the top. So if I follow your diagram, but leave only a 25-50mm air gap, it would be the best option, right?

It would seem to be your only option ! As your air gap is so tight it might not be a bad idea in your case to keep with the high density insulation that you were first planing to use, otherwise if you use the wicks when it expands from being rapped up you will lose the air gap.

Originally Posted by FunkyMunkey

Considering Green Glue is supposed to be good for low frequencies, could I take off the the head plate, green glue a 100mm piece of plasterboard to the ceiling so that its edge is flush with the edge of the stud wall, then re-attach the head plate to that (see attached image). If I did a similar thing at floor level, would this reduce flanking noise? Or am I talking complete balls?!

You've completely lost me with the head plate what do you mean by it?

Originally Posted by FunkyMunkey

Also, I will eventually be mounting an LCD on the wall and want to hide the wires. I was planning to run some trunking behind the plasterboard with small between drywall mounting boxes (see second attached image). Is this a no-no in terms of soundproofing, or will the effect be negligible?

Why not just run the wires lose in the air gap that you will be creating? Either way providing you seal up any gaps in the insulation were the cables come through/trunking, then you will be fine. In a ideal world with infinite budgets and no concern for finish you would look at other ways (ie a key hole size hole will allow 30db of sound to escape, and your a better man than me if you can make your room so air tight that that doesnt exsit!). Anyhow in regards the cabling etc in the insulation then the effect is minable providing you seal any air gaps through the insulation.

Originally Posted by FunkyMunkey

Finally the side walls are wonky, too, so there are gaps of up to 1cm between the end studs and the walls they're screwed to. I was thinking of filling the bigger gaps with expanding foam and the smaller gaps with acoustic sealant. Any thoughts on this?

New house arn't much better! I take it you are talking about the wooden (not aliminuim i assume) end studs that are screwed to the wall holding the frame in place? In which case i would advise leaving the gaps that are present their as it producing (all be it smaller) a air gap (in places) between the wood and the wall. If you really wont to do someting between the wood and the wall, then fit a rubber mat between the wood and the wall were the two touch (if you can) to minimise the amount of impact sound that can past through.

With sound proofing you could easly spend 1000's of pounds trying to cover all the bases and still easly miss some! Ie way not rip out the suspend wooden floor and lay a concrete one! That way you sort the floor out for good, a line has to be drawn somewhere

[Lizard]

I don't no what your setup is 5.1 etc or what your budget is, but if you can then it is a good idea to run speaker wires in the air gap in the wall to were you will be (if ever) placing your rear speakers and even front if you wish. QED do some banna plug plug in sockets that you can fit flush to the wall (like light switches) that you can plug cables into.

Also as all your sockets will have to be moved, have you concered adding more if needed, i fitted 4 double sockets were my stuff goes and i wish now i had fitted twice as many!

Finally as you are planing to fit an LCD later, have you made sure that were you will be fitting it to the wall a firm fitting will be possible? You might want to add some extra timber noggings (think thats the term) between the studs to allow screws of the holder to grip into

[FunkyMunkey]

Originally Posted by Lizard

It would seem to be your only option ! As your air gap is so tight it might not be a bad idea in your case to keep with the high density insulation that you were first planing to use, otherwise if you use the wicks when it expands from being rapped up you will lose the air gap.

I've decided to go for the Wickes 50mm stuff, and it's in the wall now. I've glued it between the studs, so it should stay put. Also, being the extremely finickity person i am, I've stuck some thin pieces of insulation to the back of the studs, but there's still a air gap between them and the party wall

Originally Posted by Lizard

You've completely lost me with the head plate what do you mean by it?

Don't worry... it's too late now!

Originally Posted by Lizard

I don't no what your setup is 5.1 etc or what your budget is, but if you can then it is a good idea to run speaker wires in the air gap in the wall to were you will be (if ever) placing your rear speakers and even front if you wish. QED do some banna plug plug in sockets that you can fit flush to the wall (like light switches) that you can plug cables into.

Great minds think alike: I've already run the rear speaker cable for my 5.1 setup under the floor and bought a wall plate!

Originally Posted by Lizard

Finally as you are planing to fit an LCD later, have you made sure that were you will be fitting it to the wall a firm fitting will be possible? You might want to add some extra timber noggings (think thats the term) between the studs to allow screws of the holder to grip into

Yup, that's all been worked out.

I'll post some photos once I'm a bit further along.

Cheers!