Vapour barrier disaster.

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Hi all,

My first post here and I guess, rightly, it belongs in the DIY disaster section. I could really do with some sort of advice or suggestions here.

Ok, here's the deal, the short story is that I have fitted a "vapour barrier" on the wrong side of a stud wall. The longer version is that last year we decided to redo the entire kitchen. This involved taking all the walls back to the brick. One wall was soaking, it is sandstone. So we decided the best way to keep out this moisture was to put polyethene against it and built a 3 by 2 stud wall in front of it. We built the stud, filled it with insulation and put plasterboard over it. No problem so far. Months later the plaster skimmed over the wall. It was a few days later we noticed small amounts of water seaming under the stud onto the kitchen floorboards. Not really thinking too much of it we sort of put it down to the wet plaster.

We now know different. It is condensation that is forming on the polyethene against the external wall. I know, I really do know the solution is to take off the plaster board, take out the insulation and rip out the polyethene and then reinstate it all. This is the best solution but we need another because this wall now as fitted units against it. Not only that my better half would kill me at even suggesting ripping it all out.

Please guys could anybody suggest anything, could I ventilate it? Maybe cut into the plaster and insulation and allow air to flow over the polythene? This does seem self defeating, allowing cold air in and warm air out but would it help? there is room on the wall from a small radiator also, would this help?

I really am clutching at straws here, as I know what the obvious solution is but the feeling of impending doom and the wraith of my wife at the thought of ripping out brand new fitted units is not really the Xmas I am really looking forward to.

Any suggestions would be really welcome.

Cheers, Kev.
 
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Is there any void between the stud wall and the existing? Think you may be snookered!

You'll get a small response here I've ask the mods to move it to the Building section.
 
Yes there is a void of about one inch between the polyethene and the stud wall but I think you are right I am snookered here :(

Thanks for asking the mods to move it to the building section.

Kev.
 
Ventilation will just introduce warm moist air into the wall to add to your condensation problem.

If you are sure it is condensation, then you need to put another vapour barrier behind the plasterboard, or use foil backed plasterboard.
 
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As woody says, you could just put extra robust layers of VCL on the correct side.

It "might" work at stopping condensation, but then you would have to remove the unit anyway to do it, and then there is the issue of the already existing moisture in the wall, it hasn't got anywhere to go so.....

I think you'd best bite the bullet.
 
You could remove a section of the outside wall and then rip as much as you can get hold off and then another section and so on.
 
Cheers for the replies, I was pretty much resigned to it and was kind of hoping against hope there may be some sort of fix. But realistically the only fix is to get rid of the polythene. I think I will take off the plasterboard (and units), take out the insulation and get rid of the polythene. Then reinstate it all without the polythene. I actually cut out a small section of the board and insulation this afternoon and felt the polythene behind it all. It was soaking as far as I could reach. I am kind of hoping I will be able to leave the wall units in place and just remove lower sections of plaster board and pull it all out from below but either way from what was nearly a finsihed job it looks like it is virually going back to square one :cry:

I am guessing the route cause is condensation forming on the polythene, running down it onto the floor behind the stud wall and seeping through into the kitchen.

Oh well, lessons learnt and all that. One thing for sure, I won’t be breaking this news until after Xmas. Thanks for all your input and hope everybody as a great Xmas.

Kev.
 
You don't need to remove the polythene, only prevent moisture from getting behind the plasterboard and into the wall
 
A solution might be to buy her a box of chocolates and a pair of Jimmy Choos.
 
:LOL: Haha Great advice but I think this is going to take a little bit more than a box of chocolates and a pair of shoes, but hey you never know !!

Kevin.
 
You don't need to remove the polythene, only prevent moisture from getting behind the plasterboard and into the wall

Correct.

But I don't see how he can do that without removing the units, and if you remove the units you may as well do it proper.


The idea is to make sure the warm side is more vapour impermeable than the cold side, extra thick robust, taped and lapped VCL on the plasterboard may give you a favourable impermeable vs permeable ratio, but already existing moisture may sit in there for a long period.
 
Hi everybody,

Just a quick update on this issue and a further question for you guys, if you don’t mind. Ok the deal is I now removed all the polythene from behind the stud wall (don’t ask!!). So now the stud wall is being reinstated with just the insulation (king span) between the wooden frames. This wall stands away from the external sandstone wall which is still soaking.

The internal stud wall covers, in one corner quite a large void (there used to be an external door there). Rather than follow the void round with the new stud I build a straight wall. So basically in this corner is a two, maybe three foot void between the external wall and internal stud. Here is where the water seems to be really concentrated. The entire area is absolutely soaking, even with the polythene out.

So the question, what to do about it? I am thinking that a vent on the external wall into this area would help clear out this moisture and keep it down. Does anybody disagree with this? At this moment I really want to sort this out and not want to revisit this problem later on.

Any suggestion on keeping moisture down (permanently) in this void would be more than welcome.

Oh and no buying shoes was never going to work. I was told in no uncertain terms where they would go and it wasn’t the void space behind wall!! :LOL:

Kev.
 
Vapour barrier plaster board and most cavity walls have vents. Get a humidifier to help dry the walls.
 

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