Damp found on kitchen wall - HELP!!

[Jim]

Hi all

Started removing the tiles in my kitchen and I've found an area of damp !! The wall in question is what was the old exterior wall but is now an interior as an extension was added quite a while ago (guessing about 20 years) The wall is block (possibly brick) with a plaster coat, then someone has plasterboarded over that and stuck the tiles to the plasterboard. Ther area of damp is at least 3 foot across (maybe more but that goes into another room) and stretches 2 feet up the wall. The plasterboard was damp to the touch and black but the wall underneath doesn't appear too bad.

Can anyone advise what my next course of action should be as I've never had to tackle damp before

Thanks

Jim

[Stuart Noble]

With that much damp on an internal wall, I think I'd check for plumbing leaks first.

[Johan]

If the wall is indeed fairly dry, then "all" you need to do is find the cause of the damp and remove it. Things to look at:

Is it not just water going through the tiles (is it behind the sink area)? Can it be a leaking water supply or waste pipe? Condensation on a cold water supply pipe?

Also, is the floor (damp) concrete, and did the plasterboard or plaster touch this and draw up damp?

If you're an experienced diy-er, you will already have thought about all this, I guess. Just my tuppence worth.....

Johan

[Jim]

I did find a couple of water pipes under the palsterboard chased into the brickwork but these didn't have any obvious leaks. With regard to condensation would it help if I stuffed some loft type insulation round these ?

Hard to tell if the floor itself was damp as it is tiled. There is now a couple of cm gap between the brickwork and floor tiles that I've swept out of loose debris although it feels slightly damp this could just be that it's cold or that it is where the palsterboard was touching it. Would putting a plastic membrane/ laying a bead of silicone in there be any help ? Also would it be benfecial not to replace the plasterboard and tile directly onto the wall ?

Many Thanks

Jim

[Rednadnerb]

What kind of finish are you planning instead of the tiles? It may be that the wall was tiled over in the first place because of a small damp issue and then the air couldn't get to it so now it looks worse than it was before. If you have ruled out a pipe leak then the usual option is to take it back to the brickwork up to a metre and then render it with sand and cement with a waterproofing additive. But if as you say, the brickwork is dry then this may sound like overkill but now you've started hacking it off you have to put something back on. Tiles?

[Stuart Noble]

Not usual for internal walls though.

[Johan]

Assuming the pipes are still exposed now, you will be able to see whether condensation is the problem. Or indeed a slow (tiny) leak.

I would think that as long as the cause of the damp is not established, it is hard to know whether and how it would be possible to ignore and hide it. And it would possibly cause more trouble in the future.

[mail]

Dear Jim There are four categories of damp in houses Rising (hygroscopic salt contamination over decades) Lateral penetration (of rain or ground water depending if it is above or below ground) Condesation Pipe leaks (internal or external)

You need to find out which is the cause

=46rom what I have read it is likely to be rising damp from the time it was an external wall which has been covered up

It could be a current source perhaps by bridging but that is less likely

What to do? Well first of all - map it and see where it is - use a resistance meter if you can borrow one This should give you a clue as to where it is coming from

Then check the original plaster and patches of mortar (by removing plaster in parts) and if you get high readings from both mortar and plaster it is likely to be RD

IF and only if past RD is confirmed (ie hygroscopic salts) you need to hack off and then after it has had a chance to dry out (rake out pointing mortar) re render and possibly install a dpc

If original plaster is not hygroscopic use that to put cross battening and Wedi board for the new tiles

Send me a plan section and photos and I can probably firm up on likely cause and best response Chris

[Jim]

Dear Jim There are four categories of damp in houses Rising (hygroscopic salt contamination over decades) Lateral penetration (of rain or ground water depending if it is above or below ground) Condesation Pipe leaks (internal or external)

You need to find out which is the cause

From what I have read it is likely to be rising damp from the time it was an external wall which has been covered up

It could be a current source perhaps by bridging but that is less likely

What to do? Well first of all - map it and see where it is - use a resistance meter if you can borrow one This should give you a clue as to where it is coming from

Then check the original plaster and patches of mortar (by removing plaster in parts) and if you get high readings from both mortar and plaster it is likely to be RD

IF and only if past RD is confirmed (ie hygroscopic salts) you need to hack off and then after it has had a chance to dry out (rake out pointing mortar) re render and possibly install a dpc

If original plaster is not hygroscopic use that to put cross battening and Wedi board for the new tiles

Send me a plan section and photos and I can probably firm up on likely cause and best response Chris

Thanks Chris for the detailled answer and offer of help.

I saw a 'damp meter' in Aldi the other week so may pop along to see if they still have them. Sure it won't be the most accurate item in the world but hopefully good enough to do the job. Once I've got some results I follow up.

Cheers

Jim

[Davao]

It might be the roof join of the new extension and original. My neighnour used to have a small forest growing in the guttering and assumed it was crap collecting in the gutter. I've also had a long standing dampness problem in the shared wall below this section of guttering causing dampness in the bathroom and kitchen below it. The neighbour had it fixed recently and this cured all of the dampness.

Arthur