Dot and Dab Plasterboard Installed. Very Noisy!!

graeme16

Hi,

We have been renovating a house we bought earlier this year and there are some posts on here from myself where we decided to strip back the old blown lime plaster and have the entire house dot & dabbed. The plasterers are finishing up today and yesterday I went into the lounge which has the adjoining wall to the neighbours and I could hear the neighbours really loud. As if they were standing behind a super thin studded wall with no insulation. There are chimney breasts in all the rooms and in the lounge the sound appeared to be coming mainly from the alcove next tot he chimney breast which I guess is the thinnest part of the adjoining wall.

We are somewhat getting over the disappointment of this potential problem and thinking of resolutions. We haven't yet had the skirting / architrave put on and no paint so now is the time to complete any remedial works. From some quick research it would appear we have essentially turned the adjoining wall into a huge drum skin with the air gap behind the plasterboard resonating board. I initially though of drilling lots of holes and filling with expanding foam to prevent the board from vibrating as much but I cant find anything to suggest this would be effective. 

Two potential fixes I am thinking are:

• Pulling the Dot & Dab of each of the adjoining walls of the house in the alcoves and building a stud wall, filling with rockwell insulation, fixing acoustic insulation plasterboard board and reskimming.

• Pulling the Dot and Dab of of the entire adjoining walls and wet plastering these, including the chimney breasts to 'replicate' the original lime plaster as best we can. We could potentially double up on the cement / bonding coat in the alcoves to further enhance the soundproofing.

Does anyone have any thoughts / experience on the above? 

graeme16

Do the Chimney breasts need soundproofing or they more 'immune' due to the thickness of them?

FreeBear

The lime plaster would have been fairly thick, and certainly heavy. This would absorb a fair percentage of the noise coming through the party wall. Bunging up dot'n'dab plasterboard is in effect, installing a drum skin. Injecting expanding foam into the void will cut down on the drum skin effect, but you risk pushing the plasterboard away from the wall and breaking the dot'n'dab bonds. If you strip out the (new) plasterboard and fix sound blocking PB in its place, you really need to cover both the wall and PB with adhesive (100% coverage) to avoid the drum skin effect. Two layers of sound blocking PB should give you the same mass as the original lime plaster. May not cut all the noise out though..

Fixing studs to the wall and infill the gaps with acoustic rockwool batts (not regular insulation batts), and again topped off with a double layer of sound blocking PB should kill most of the noise. You will still get some noise/vibrations bleeding round the edges and at floor/ceiling level. Not much you can do about that without a serious amount of work.

The chimney breast shouldn't be transmitting too much in the way of noise. It will have a substantial mass which helps to cut down on noise transmission.

grumbler

I don't believe that replacing the original plaster with dot&dab can make things worse.
Also, I think that 'acustic' plasterboard is marketing gimmick.
For a real result you need a studwall, but filled with acustic rockwool insulation, not just rockwool. And get the studs fixed to the floor and the ceiling, not to the wall. Even better leave a small few mil gap.

plumb1_2

Insulated plasterboard 

graeme16

Thanks for the replies. It seems as though creating a false wall between the floor and the ceiling joists and filling with insulation is the favoured option. My worry is regarding the chimney breasts and whether noise will still come through there.

It's difficult to judge because at present there are still floorboards missing, no underlay / carpet down etc. so this is worse case but it did sound as though there was a lot travelling through the walls.

Just debating whether it would be better to float and set the entire walls including the chimney breasts or just stud the alcoves. .  .

FreeBear

Used to have bookshelves in the alcoves here. Would hear a little bit of noise from next door. After clearing out the alcoves, the noise levels increased noticeably. It is/was mass cutting down on noise. As mentioned earlier, the chimney breast is a substantial lump of brickwork, so there is little to be gained putting soundproofing round it.

If you ever plan on having a wood stove in the fireplace, you don't really want plasterboard or gypsum plaster in the vicinity - The stuff cracks & flakes when exposed to temperatures above 50°C.

fenwick458

my guess is pin hole gaps in the wall(which would have been sealed with the old plaster) are now exposed, allowing free travel of sound through the wall. So I'd go for option 2, hack off the plasterboards, and scratch a layer of sand cement on the wall, then dot n dab the wall again
I had a fireplace knocked out on a dividing wall once and the wall was then skimmed, after it was done I could hear the neighbours way more than before. Ended up chipping the plaster off around the old lintel level to find a few 50-75mm gaps that were filled with foam and then skimmed over, and even full bricks foamed in and skimmed over. once I pieced it all back in with sand cement and patched it in it's been fine. Mass stops sound travelling

Mr.Generous

Before I did anything too drastic or expensive I'd be tempted to try that Warmaline stuff, 2mm Polystyrene veneer, then lining paper and wallpaper over it. Got to help - it would have to deaden the noise a bit.

graeme16

Thanks for all the comments. We think it has to be the Dot & Dab has created a resonance chamber as we have been to the house tonight and you can hear the noise throughout the entire house. I have had the old lime mortar stripped off in the lounge for many weeks with many evenings working at the house right next to the exposed lounge wall. 

Plan is to strip the plasterboard off in the lounge, which seems to where the majority of the noise is emanating from and see if there is an improvement. If there is we will pull the plaster board off all the party walls and wet plaster the lot. We can then use that as a base to add other acoustic layers if required or just skim straight onto that if we are happy with the noise reduction.