Just had the exterior of a Victorian house repainted/re-rendered. The solid
walls
are about 450mm thick. There was penetrating damp on some of the inside
wall.
These walls are still damp but we assume that it will take some time for the
the
brickwork to dry out. (In fact some of the internal damp seems to have got
worse - probably because it is now less easy for trapped damp it to escape
externally).

The building is about 15m high. Damp occurs at all levels. How long is
reasonable
to wait before we can expect the inside to be dry, assuming the source of
damp
has now been eliminated? The building is well ventilated and it is not
condensation.

regards,
Andrew

In article <431ed1c2$0$17500$ed2e19e4@ptn-nntp-reader04.plus.net>, 
"Andrew" <-> says...

> Just had the exterior of a Victorian house repainted/re-rendered. The solid
> walls
> are about 450mm thick. There was penetrating damp on some of the inside
> wall.
> These walls are still damp but we assume that it will take some time for the
> the
> brickwork to dry out. (In fact some of the internal damp seems to have got
> worse - probably because it is now less easy for trapped damp it to escape
> externally).
> 
> The building is about 15m high. Damp occurs at all levels. How long is
> reasonable
> to wait before we can expect the inside to be dry, assuming the source of
> damp
> has now been eliminated? The building is well ventilated and it is not
> condensation.
> 

Unless you rendered with lime mortar and painted with a porous paint it 
quite possibly won't go away at all.

If you have eliminated the source it can take along time to dry out
e.g. year or more. Also old lime plaster if damp for a long period can
become hygroscopic i.e. absorb atmospheric moisture. This results in
intermittent damp patches in peculiar places e.g. half way up walls,
and is most noticeable in humid weather like today or when there is a
change from cool to warm/humid. 
So give it a year or so.

cheers

Jacob

jacob@jpbutler.demon.co.uk wrote:


> If you have eliminated the source it can take along time to dry out
> e.g. year or more. Also old lime plaster if damp for a long period can
> become hygroscopic i.e. absorb atmospheric moisture. This results in
> intermittent damp patches in peculiar places e.g. half way up walls,
> and is most noticeable in humid weather like today or when there is a
> change from cool to warm/humid. 
> So give it a year or so.
> 
> cheers
> 
> Jacob
> 


I would not be so pessimistic.

IF you have no rising damp - and its a big if - 4-6weeks will take care 
of damp plaster.

If you have sodden internal brick walls, expect issues all winter but 
central heating does dry interior walls pretty effectively with cold dry 
air outside.

If you haven't fixed the rising damp, then as another poster has bluntly 
put it, with a waterproof covering in the outside, you will get 
perpetual damp inside.

Its not clear exactly what is damp, whether damp proof or breathable 
membranes are, or what construction the house is, and its insulation 
standard.

All these make substantial differences.

Rob Morley wrote:

> In article <431ed1c2$0$17500$ed2e19e4@ptn-nntp-reader04.plus.net>, 
> "Andrew" <-> says...
> 
>>Just had the exterior of a Victorian house repainted/re-rendered. The solid
>>walls
>>are about 450mm thick. There was penetrating damp on some of the inside
>>wall.
>>These walls are still damp but we assume that it will take some time for the
>>the
>>brickwork to dry out. (In fact some of the internal damp seems to have got
>>worse - probably because it is now less easy for trapped damp it to escape
>>externally).
>>
>>The building is about 15m high. Damp occurs at all levels. How long is
>>reasonable
>>to wait before we can expect the inside to be dry, assuming the source of
>>damp
>>has now been eliminated? The building is well ventilated and it is not
>>condensation.
>>
> 
> Unless you rendered with lime mortar and painted with a porous paint it 
> quite possibly won't go away at all.


I'm sure the OP will be pleased to hear that! Unless he runs a laundry 
and has no heating, I'm sure the damp will dry out just fine since it 
will presumably no longer be pouring through from outside.

Where do you find these plasterers that are prepared to bugger about 
covering whole walls with wet sacks? Do they smoke clay pipes?
And what the hell use is porous paint? All water based paint is porous, 
as you soon discover if you use it to cure penetrating damp. Pliolite 
resins are a *major* improvement in masonry paint but even they are far 
from being impermeable.

"Stuart Noble"  wrote in message
news:BkGTe.401$9p3.95@newsfe7-win.ntli.net...

> Rob Morley wrote:
> > In article <431ed1c2$0$17500$ed2e19e4@ptn-nntp-reader04.plus.net>,
> > "Andrew" <-> says...
> >
> >>Just had the exterior of a Victorian house repainted/re-rendered. The
solid
> >>walls
> >>are about 450mm thick. There was penetrating damp on some of the inside
> >>wall.

> >
> > Unless you rendered with lime mortar and painted with a porous paint it
> > quite possibly won't go away at all.
>
> I'm sure the OP will be pleased to hear that! Unless he runs a laundry
> and has no heating, I'm sure the damp will dry out just fine since it
> will presumably no longer be pouring through from outside.
>


Mention damp and period buildings on the internet and you can guarantee an
instant if-it's-not-lime-your-doomed response. Apart from for really old
buildings,
I've never come across builders in the real world even mention the stuff.

As my house has had a concrete render for least 100 years, replacing it all
with lime seems overkill and probably unnecessary, even if it was an option.
If the damp doesn't dry out, I'll just paint over it and manage the problem.
However, from the responses received I guess I should wait a few months
to see if the problem is cured.

regards,
Andrew

In article <431ffb83$0$97122$ed2619ec@ptn-nntp-reader03.plus.net>, 
"Andrew" <-> says...

> 
> "Stuart Noble"  wrote in message
> news:BkGTe.401$9p3.95@newsfe7-win.ntli.net...
> > Rob Morley wrote:
> > > In article <431ed1c2$0$17500$ed2e19e4@ptn-nntp-reader04.plus.net>,
> > > "Andrew" <-> says...
> > >
> > >>Just had the exterior of a Victorian house repainted/re-rendered. The
> solid
> > >>walls
> > >>are about 450mm thick. There was penetrating damp on some of the inside
> > >>wall.
> 
> > >
> > > Unless you rendered with lime mortar and painted with a porous paint it
> > > quite possibly won't go away at all.
> >
> > I'm sure the OP will be pleased to hear that! Unless he runs a laundry
> > and has no heating, I'm sure the damp will dry out just fine since it
> > will presumably no longer be pouring through from outside.
> >
> 
> Mention damp and period buildings on the internet and you can guarantee an
> instant if-it's-not-lime-your-doomed response.


I was surprised I was the only one - someone has to do it, it's 
traditional  :-)

Andrew wrote:


> > >>Just had the exterior of a Victorian house repainted/re-rendered. The
> solid
> > >>walls
> > >>are about 450mm thick. There was penetrating damp on some of the inside
> > >>wall.


You never told us what you did to solve the damp problem. If
rerendering was it, it may or may not dry out, its not really a good
solution to damp.


NT

bigcat@meeow.co.uk wrote:

> Andrew wrote:
> 
> 
>>>>>Just had the exterior of a Victorian house repainted/re-rendered. The
>>
>>solid
>>
>>>>>walls
>>>>>are about 450mm thick. There was penetrating damp on some of the inside
>>>>>wall.
> 
> 
> You never told us what you did to solve the damp problem. If
> rerendering was it, it may or may not dry out, its not really a good
> solution to damp.



It's often the only solution short of re-building the house. If water is 
prevented from entering the wall from the outside, why wouldn't the 
inside dry out?

In article <qA_Te.1391$Q%2.1202@newsfe1-win.ntli.net>, 
stuart_nobleNOSPAM@ntlworld.com says...

> bigcat@meeow.co.uk wrote:
> > Andrew wrote:
> > 
> > 
> >>>>>Just had the exterior of a Victorian house repainted/re-rendered. The
> >>
> >>solid
> >>
> >>>>>walls
> >>>>>are about 450mm thick. There was penetrating damp on some of the inside
> >>>>>wall.
> > 
> > 
> > You never told us what you did to solve the damp problem. If
> > rerendering was it, it may or may not dry out, its not really a good
> > solution to damp.
> 
> 
> It's often the only solution short of re-building the house. If water is 
> prevented from entering the wall from the outside, why wouldn't the 
> inside dry out?
> 

Because moisture also comes from inside and below?

Rob Morley wrote:

> In article <qA_Te.1391$Q%2.1202@newsfe1-win.ntli.net>, 
> stuart_nobleNOSPAM@ntlworld.com says...
> 
>>bigcat@meeow.co.uk wrote:
>>
>>>Andrew wrote:
>>>
>>>
>>>
>>>>>>>Just had the exterior of a Victorian house repainted/re-rendered. The
>>>>
>>>>solid
>>>>
>>>>
>>>>>>>walls
>>>>>>>are about 450mm thick. There was penetrating damp on some of the inside
>>>>>>>wall.
>>>
>>>
>>>You never told us what you did to solve the damp problem. If
>>>rerendering was it, it may or may not dry out, its not really a good
>>>solution to damp.
>>
>>
>>It's often the only solution short of re-building the house. If water is 
>>prevented from entering the wall from the outside, why wouldn't the 
>>inside dry out?
>>
> 
> Because moisture also comes from inside and below?


Lime lovers seem to have the idea that human activity generates buckets 
of water that are prevented from evaporating by cement and/or a coat of 
Dulux on the outside of the house. With normal heating and ventilation 
this source of moisture shouldn't be an issue. If water is entering from 
below then you need to stop it rather than accommodating damp as a way 
of life. It really isn't very healthy

I hate to be a wet blanket, but bear with me for a while.
..
In 1994 I replaced a coal boiler with a gas combi. In 1999
water was running down the living room wall. After eliminating
the obvious candidates, slates, flaunching, pointing, flashing
etc I was left with only one option - the flue (the products of
combustion are carbon dioxide and water). This proved to be the
case. It had been damaged on installation and, for five years had
been pumping water into a 75cm shale wall with soil/lime mortar.
The flue was replaced.
..
Six years on, the wall is still not completely dry despite my having,
this year, chopped off and repointed the bottom metre of external
rendering and run a 2kw fire and a dehumidifier in the sealed room for
8 - 10 hours a day.
..
Another side effect (this is speculation)is that the formerly sound
rendering has been loosened by winter frost action on the moisture in
the wall, so I may have to replace this as well.
..
The moral of this story is to assume nothing about the behaviour of
damp. All you can do is find its source, block it, do what you can to
dry it, then wait, wait, wait.
..
The mystery, to me, is why, in this age of technological wizardry, when
probes can be landed on other planets and the evolution of a life can
be tracked from ejaculation to delivery, there is no simple hand held
device which, either electronically or seismologically, can detect the
precise location of moisture in a wall. Moisture meters are a nonsense:
they tell you what you can see or, by running your hand over the wall,
feel, but tell you nothing (without drilling) about what is happening
within it.

Tony.

On 10 Sep 2005 12:24:47 -0700, tonybo@evemail.net wrote:

| I hate to be a wet blanket, but bear with me for a while.
| .
| In 1994 I replaced a coal boiler with a gas combi. In 1999
| water was running down the living room wall. After eliminating
| the obvious candidates, slates, flaunching, pointing, flashing
| etc I was left with only one option - the flue (the products of
| combustion are carbon dioxide and water). This proved to be the
| case. It had been damaged on installation and, for five years had
| been pumping water into a 75cm shale wall with soil/lime mortar.
| The flue was replaced.
| .
| Six years on, the wall is still not completely dry despite my having,
| this year, chopped off and repointed the bottom metre of external
| rendering and run a 2kw fire and a dehumidifier in the sealed room for
| 8 - 10 hours a day.
| .
| Another side effect (this is speculation)is that the formerly sound
| rendering has been loosened by winter frost action on the moisture in
| the wall, so I may have to replace this as well.
| .
| The moral of this story is to assume nothing about the behaviour of
| damp. All you can do is find its source, block it, do what you can to
| dry it, then wait, wait, wait.
| .
| The mystery, to me, is why, in this age of technological wizardry, when
| probes can be landed on other planets and the evolution of a life can
| be tracked from ejaculation to delivery, there is no simple hand held
| device which, either electronically or seismologically, can detect the
| precise location of moisture in a wall. Moisture meters are a nonsense:
| they tell you what you can see or, by running your hand over the wall,
| feel, but tell you nothing (without drilling) about what is happening
| within it.
| 
| Tony.

-- 
Dave Fawthrop <dave hyphenologist co uk> 
"Intelligent Design?" my knees say *not*.
"Intelligent Design?" my back says *not*.

How the hell did Dave Fawthrop become the author of my post? I bet he's
wondering too.

Tony.

On 10 Sep 2005 12:24:47 -0700, tonybo@evemail.net wrote:


>In 1994 I replaced a coal boiler with a gas combi. In 1999
>water was running down the living room wall. After eliminating
>the obvious candidates, slates, flaunching, pointing, flashing
>etc I was left with only one option - the flue (the products of
>combustion are carbon dioxide and water). This proved to be the
>case. It had been damaged on installation and, for five years had
>been pumping water into a 75cm shale wall with soil/lime mortar.
>The flue was replaced.
>.
>Six years on, the wall is still not completely dry despite my having,
>this year, chopped off and repointed the bottom metre of external
>rendering and run a 2kw fire and a dehumidifier in the sealed room for
>8 - 10 hours a day.


Are you sure you don't have another source of damp?

DG

In article , 
tonybo@evemail.net says...

> How the hell did Dave Fawthrop become the author of my post? I bet he's
> wondering too.
> 

He didn't, although he has apparently reposted it in its entirety 
without adding any of his own comments.  Do you understand how quoting 
and attributions work on Usenet?

On 10 Sep 2005 12:52:19 -0700, tonybo@evemail.net wrote:

| How the hell did Dave Fawthrop become the author of my post? I bet he's
| wondering too.

If you look you will find that I quoted it.
I was going to follow up and hit the wrong button :-(
-- 
Dave Fawthrop <dave hyphenologist co uk> 
"Intelligent Design?" my knees say *not*.
"Intelligent Design?" my back says *not*.

In article ,
   Dave Fawthrop  wrote:

> If you look you will find that I quoted it.
> I was going to follow up and hit the wrong button :-(


A decent newsreader should then throw up a warning of 'no unquoted text'
and ask for confirmation. ;-)

-- 
*60-year-old, one owner - needs parts, make offer

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

>Are you sure you don't have another source of damp?


Yes. The water was trapped between internal (which had been plastered
over) and external rendering and it was simply hydrostatic pressure
that eventually forced it into the house. In any case, unlesss every
cat for 50 miles is climbing on my roof, nightly, to urinate on the
rendering (I think I'd have noticed (:- ) rain is the only possible
source - and we've had very little of that in this area in the last 2
or 3 years. But if you have a credible  alternative, I'm listening. The
novelty of bare plaster in the living room is beginning to pall.

Tony.

On 11 Sep 2005 08:06:20 -0700, tonybo@evemail.net wrote:


>>Are you sure you don't have another source of damp?
>
>Yes. The water was trapped between internal (which had been plastered
>over) and external rendering and it was simply hydrostatic pressure


A 75 cm thick wall full of water ?  :((


>that eventually forced it into the house. In any case, unlesss every
>cat for 50 miles is climbing on my roof, nightly, to urinate on the
>rendering (I think I'd have noticed (:- ) rain is the only possible
>source - and we've had very little of that in this area in the last 2
>or 3 years. But if you have a credible  alternative, I'm listening. The
>novelty of bare plaster in the living room is beginning to pall.
>


How much does the dehumidifier collect in it's 8 hour session?

Noticing that my vacuum foodsealer sucks moisture vigorously out of
stuff such as onions I wonder if sealing the area with a visqueen
membrane using flexible RTV and vacuum  pumping it out with an
aspirator  (killing 2 birds with one stone) might work? 

http://en.wikipedia.org/wiki/Aspirator

http://hyperphysics.phy-astr.gsu.edu/hbase/fluids/aspir.html

Be Careful ! see pics...

Possible snag, onions are of course compressible walls are not. But if
the wall is permeable enough it might be worth a try.  

I want a Nobel prize if it works.

DG

>How much does the dehumidifier collect in it's 8 hour session?


About 3 pints. The arithmetic is, to me at least, interesting.

The wall has a total volume of about 1,814, 400 cu in, and the split in
the flue was near the top, so the whole wall was soaked. If 10% were
water and it dried in 6 years (2190 days) it would mean that
181440/2190 cu in would have to be released, on average, daily i.e.
2.4pts which, taking into account atmospheric moisture ( the windows
are open for the other 14-16 hours) and the fact that the dehumidifier
and heating have accelerated the process recently, is not too far from
what I was getting.

A curious feature, which supports my contention that the water is
trapped between the 2 coats of render, is that turning off the
dehumidifier, during the last week or so, causes the internal wall to
become drier, leaving gravity, and the air, working on the newly
exposed lower part of the outside, to take over the drying. When the
dehumidifier is on, the resultant dry atmosphere, internally, causes
moisture to be drawn into the house.

Of course, this is all ifs buts and maybes, but I'm fairly confident
that my reasoning is sound, even if the estimates are no more than
guesses, and a little less confident that the end is in sight. Please
God, don't make it more than 10%(:-

Tony/

tonybo@evemail.net wrote:

> >How much does the dehumidifier collect in it's 8 hour session?
>
> About 3 pints. The arithmetic is, to me at least, interesting.
>
> The wall has a total volume of about 1,814, 400 cu in, and the split in
> the flue was near the top, so the whole wall was soaked. If 10% were
> water and it dried in 6 years (2190 days) it would mean that
> 181440/2190 cu in would have to be released, on average, daily i.e.
> 2.4pts which, taking into account atmospheric moisture ( the windows
> are open for the other 14-16 hours) and the fact that the dehumidifier
> and heating have accelerated the process recently, is not too far from
> what I was getting.
>
> A curious feature, which supports my contention that the water is
> trapped between the 2 coats of render, is that turning off the
> dehumidifier, during the last week or so, causes the internal wall to
> become drier, leaving gravity, and the air, working on the newly
> exposed lower part of the outside, to take over the drying. When the
> dehumidifier is on, the resultant dry atmosphere, internally, causes
> moisture to be drawn into the house.
>
> Of course, this is all ifs buts and maybes, but I'm fairly confident
> that my reasoning is sound, even if the estimates are no more than
> guesses, and a little less confident that the end is in sight. Please
> God, don't make it more than 10%(:-
>
> Tony/



I'm far from convinced. Few walls are so watertight, not one single
crack anywhere, impermeable bottom, than free water can not escape. If
yours were filled with free water, and sealed like a Roman pool (not
easy even when trying) one small drill hole would empty it.

I expect you have an ongoing source of damp. I would check the property
over for all the usual causes of damp.


NT

tonybo@evemail.net wrote:


> A curious feature, which supports my contention that the water is
> trapped between the 2 coats of render


I can't see that it's possible to "trap" water between 2 coats of 
something permeable. But if water pours in at a specific point when it 
rains and then has to dry out gradually by evaporation, the wall may 
well give the impression of being permanently soaked.

> I would check the property
>over for all the usual causes of damp.


See paragraph 2 of my post on September 10th. That's where I started,
and have checked since.

Tony.

>I can't see that it's possible to "trap" water between 2 coats of
>something permeable. But if water pours in at a specific point when it
>rains and then has to dry out gradually by evaporation, the wall may
>well give the impression of being permanently soaked.


I was using the word 'trap' loosely. The wall is enclosed  by 4:1
cement render. In this part of the world just about everything is a 4:1
mix. I didn't put it there, nor would I have, but I've learned from
experience that the locals have their own way of doing things, based on
their experience.

As I said previously, we've had little rain for a long time but, when
it happens, the wall gets no wetter.

Tony.