[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]

Jim wrote:
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



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

[johan]

Jim wrote:
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


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]

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

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]

On 6 Apr, 11:05, "Jim" wrote:
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

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]

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.

Not usual for internal walls though.

[johan]

Jim wrote:
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

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 ?

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


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 ?

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.


Many Thanks

Jim

[[email protected]]

On 6 Apr, 11:05, "Jim" wrote:
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

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

[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]

Jim wrote:
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




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