Sound Insulation on party walls

Charlie-Bravo

Ok, my mate calls me and asks how do you sound insulate a party wall. I said we should research the best options and then thought, sure, the guys on boards will be very helpful for this problem. So here's the detail...

My mate hears the neighbours talking in the room next door of the adjacent house while he's in bed! Sure, they could be hearing him while he's in bed Anyways, the wall is probably a 225 blockwork on flat (late 70's/early 80s semi-detached house). The finish is plasterboard - as I tap on the wall it makes a hollow sound...so its probably plasterboard on dabs or battens.

So what are the options and what is the best option in the end. I hear of people using Soundbloc board, but that might not solve the real problem so you could be wasting your time. I could also research all the noise reducing indexes of products but not hit the nail on the head for an adequate solution to the problem!

What I'm ask saying is, what system is best to gaurantee the best reduction in sound between the two houses based on this situation?!

Cheers in advance for your input...Astrofluff

Carlow52

astrofluff wrote: »

Ok, my mate calls me and asks how do you sound insulate a party wall. I said we should research the best options and then thought, sure, the guys on boards will be very helpful for this problem. So here's the detail...

My mate hears the neighbours talking in the room next door of the adjacent house while he's in bed! Sure, they could be hearing him while he's in bed Anyways, the wall is probably a 225 blockwork on flat (late 70's/early 80s semi-detached house). The finish is plasterboard - as I tap on the wall it makes a hollow sound...so its probably plasterboard on dabs or battens.

So what are the options and what is the best option in the end. I hear of people using Soundbloc board, but that might not solve the real problem so you could be wasting your time. I could also research all the noise reducing indexes of products but not hit the nail on the head for an adequate solution to the problem!

What I'm ask saying is, what system is best to gaurantee the best reduction in sound between the two houses based on this situation?!

Cheers in advance for your input...Astrofluff

Do a search on this forum for previous threads on this matter.

The key is the workmanship of any remedial work

I presume the party wall goes all way to roof in attic

Sound travels through the smallest of holes, so maybe the block work was done < 100%

Are there wall vents side by side from both houses?

soldsold

As carlow says there was a recent thread on sound isolation.

Most of the remedial measures that use non-standard materials are pricey.

Basically to stick with standard building materials you need to either use mass (concrete blocks, dense insulation such as rockwool, etc) or isolation (build another wall inside the separating wall with a 1 inch gap). Obviously the first solution will mean building another wall structure anyway.

The other way is to dampen the sound vibrations and turn them into heat - you add a layer or two of plasterboard with a "vibration dampening compound" (ie a mastic that never goes off) in between each layer. One layer of drywall with this "non-setting mastic" in between will give a good sound reduction and is particularly effective for low frequency sounds (bass etc), if you PM me I'll send on contact details, its what all the home cinema builders use and rave about (if you search UK site avforums.com diy cinema build section you will see what I mean). I have not used the stuff but am planning a cinems in my extension so have spent a lot of time reading up on it.

So the 2 choices are:

To lose half an inch of space - add plasterboard with a vibration dampening compound in between it and the party wall - a little bit more expensive than the next choice.

To lose 5 inches - simply build a 2x4 wall an inch from the party wall and put on 2 layers of plasterboard on your own side.

In both cases dont let the plasterboard touch the ceiling, floor or either of the side walls - leave a 5mm gap and fill with caulk. Avoid electrical outlets on this party wall.

Then as Carlow says have a look in the attic and make sure there is no flanking noise getting across. If there is, the party wall in the attic needs to be sealed if there are gaps, or built if there is no party wall

PM me with your email address and I'll send you on some more info.

FYI if building a new wall - eg between bedrooms - a double stud wall is an excellent soundproof wall. This is:

2 layers of plasterboard with staggered joints and not touching perimeter ceiling, floor or walls (5mm gap filled with caulk)
2x4 filled with fibreglass
1 inch air gap
2x4 filled with fibreglass
2 layers of plasterboard with staggered joints and not touching perimeter ceiling, floor or walls (5mm gap filled with caulk)

Steve

Mellor

astrofluff wrote: »

My mate hears the neighbours talking in the room next door of the adjacent house while he's in bed! Sure, they could be hearing him while he's in bed Anyways, the wall is probably a 225 blockwork on flat

If he can hear the neighbours talking (in normal voice, not shouting).
Then I doubt its 225 on flat. Might be lightweight, or the neighbours might shout

soldsold

Just to add to my last post:

If you have a timberframe party wall (or any separating wall) and add another timberframe 2x4 wall inside it then you risk making a "drum" effect.

So the fix is (even though it doesnt seem logical) to rip the plasterboard down from your side of the party wall (ie leave no plasterboard in between the two wall structures) and double up the plasterboard on your side (and ideally the neighbours side too).

Before you make any remedial measures always check that your neighbours have not left a baby monitor on in your house when they visited you last time (eg under the sofa)

The last line is a joke

Charlie-Bravo

thanks guys for that....and thanks soldsold for a very comprehensive post. I see where you are coming from with the electrcial sockets on the wall...I'll check for these. the workmanship I always knew would be a big factor, so I'll monitor this. With regards to a gap filled with caulk all the way round, it makes sense to do this to reduce flanking sound transmitting to the plasterboard.

I think the plan will be to remove the 'drum effect' by removing the plasterboard, fixing up battens, insulating between with rock wool flexi or similar, might even counter-batten as suggested in another thread I found. The only question is, should I use a soundblock board or would I be better off double slabbing (staggering the boards) with standard 9.5mm plasterboard and skimming thereafter?!

soldsold

Normal plasterboard should be fine, from what I understand.

The double wall will give a a very good result, if it was me I would save the extra cash.

Another option:

Put up the first layer of plasterboard and listen for noise from the other side. Even without plastering it should give an idea what it would be like.

If happy just slab the second layer and plaster.

If the best guess is that it wont do, then look at isolating material between the two plasterboard layers.

I'll PM a link to where you can compare a few different options.

Steve