Damp Proofing Question

False wall?

thank you so much everyone for there prompt and helpful advice.some more details on this, it is a basement flat and a non cavity outside wall I am having problems with.in answer to some of the questions and suggestions posted I have, over the last 15 years had various things attempted, including a foil backed plaster board ( which in my opinion has made it ten times worse.)
The ventilation is defiantly an issue but as a basement flat it is not practical to leave window open.air bricks and extractor fans sound like a good start and cheaper then a false wall.the only reason I thought a false wall might work is because I thought it could then be insulated??
I have four lovely builders from this site to come and take a look next week, so hopefully they will all come up with a sensible suggestion.I will let you know.
thank you all again for your help, what a fab site this is.

6 Answers

Best Answer

Hi Wendy,

Where is your bathroom located?
Ground floor or first floor & above?

If it's first floor & above i very much doubt it will be rising damp.

If you say the wall & floor is dripping wet,& damp is seeping up timber supports,that doesn't sound like damp or condensation to me.

Don't know about anyone else,but i suspect some sort of leak somewhere.
I just can't see moisture/condensation being that bad that it would seep up timber supports & leave everywhere else dripping wet.
You mention also it's the 'whole wall'.
If i'm assuming correctly that it is just one wall that's affected,surely if it was condensation it would affect all walls?

What have you done so far to try and cure it?

If you could give me a bit more info,might have a better guess at what the actual problem is & possible solutions to sort it for you.



Answered 28th Mar 2011

carl melady

Member since 1 Jun 2008

I wouldnt suggest building a false wall, you will only be covering up the problem.
You need to find out the source of damp first, and have this treated.
For something like this I would get a damp proof firm in, who will assess, carry out the works, and issue a gaurantee.
Lime plaster is good, as it allows the wall to breath, but you still need to erradicate damp, most damp firms use sand/cement with water proofer/chemicals in.
Why not place your job in the Post a job Section, you will then probably get better advice, than you have had with your builders.

Answered 28th Mar 2011


Member since 29 Oct 2008

Hi Wendy
unfortunately most general builders dont specialise in damp and therefore can give you a wrong diagnosis.

Firstly,do you have adequate ventilation in the bathroom?
A timed extractor fan is needed in bathrooms etc to draw the moisture out and will keep operating after room use for at least 5 mins.
If you have a extractor fan an easy way to check it is to place a sheet of toilet paper against it and see if its held in place.
About 90% of damp issues in wet areas are caused by inadequate ventilation.

Without surveying the problem i wouldnt suggest a false wall be put in.This is a very expensive process as channels,a drain and water pump are also needed.

Lime plaster is used in a lot of refurbishment and damp proofing jobs.
Its main attributes are its a good salt blocker against the salts in rising damp.
I wouldnt reccomend this either.

Is it just this room that you have noticed a problem?
if so the problen is more likely to be excessive moisture due to a ventilation problem.

If theres any signs anywhere else in your home i would suggest contacting a my builder damp proofing specialist .

Tommy (scotia property services)

Answered 28th Mar 2011


Member since 27 Jan 2009

Hi Wendy, I agree with the others regarding the false wall, However there is a product that might be worth a look at which is a heat exchange with built in extractor this allows the damp air to be drawn out and fresh air to be heated and brought into the room might be worth a look at

Answered 28th Mar 2011


Member since 15 Jun 2008

Hi Wendy, Like the others I would not suggest the false wall and most similar issues we come across are due to older properties not having a cavity wall, which just means the wall can breath. Why not try experimenting yourself by doing some of the following: 1) leave a window cracked open when it is safe to do so. 2) Do not dry anything on radiators in there. If these things help then an extractor fan as Tommy suggested is a good idea and/or perhaps air bricks.
Best Wishes From Trade Man's World

Answered 28th Mar 2011

Trade Man's World

Member since 12 Jul 2008

It is proberblly a ventilation problem. Either an air brick is going to have to be fitted or you will need an extractor fan. this will remove the condensation and damp in the air. However you will need to remove the old walls that are more than likely going to rot and have the timbers replaced. All after the ventilation is sorted first. Hope this is helpful.

Answered 28th Mar 2011

DB Plastering

Member since 1 Apr 2011

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