Chemical Damp Proof Courses & Plastering
Asher Hoskins
Hello.
Has anyone here ever treated a house using chemical damp course injection?
I'm buying a turn of the century terrace house which has somewhat of a
damp problem and I was wondering how big a job it would be to put a new
dampcourse in myself or whether I should leave it to a building preservation
company. I've got a quote for about #2000 for doing the job (although this
does include replastering) and I can get the necessary equipment and
chemicals for under #500 if I do it myself so obviously there's a large
financial incentive for doing it myself.
On a related subject, since all plaster would have to be stripped off to
a height of 3' above the floor there's going to be a lot of replastering
to be done. Am I foolish to even think about doing this replastering myself?
Asher.
--
Asher Hoskins | Finally, I'll add that adding small frogs
DoD #506 | to your coffee enhances absorption of
PGP key available | several psychogenic tannins.
as...@prl.philips.co.uk | --- from alt.drugs.caffeine FAQ
Simon Muir
In article <Dsy36...@prl.research.philips.com>, Asher Hoskins
<as...@prl.philips.co.uk> said this sort of thing:
>Hello.
>
>Has anyone here ever treated a house using chemical damp course injection?
Yes.
>I'm buying a turn of the century terrace house which has somewhat of a
>damp problem and I was wondering how big a job it would be to put a new
>dampcourse in myself or whether I should leave it to a building preservation
>company.
What material is the wall made of and how thick is it?
> I've got a quote for about #2000 for doing the job (although this
>does include replastering) and I can get the necessary equipment and
>chemicals for under #500 if I do it myself so obviously there's a large
>financial incentive for doing it myself.
It sounds even cheaper to do than when I did it 12 years ago. We're
still in the maisonette (I did the basement walls), but we've just sold
it, (kids++). No damp problems from the bit I did, but a revisit from
the professionals was necessary for their bit!
>On a related subject, since all plaster would have to be stripped off to
>a height of 3' above the floor there's going to be a lot of replastering
>to be done. Am I foolish to even think about doing this replastering myself?
3' is a bit of a challenge, but in my very limited experience, the
damage was minimal (in one room, we barely touched the plaster at all).
One caveat - the reason I had to use a professional firm at the front of
the house was for the building society, who insisted on guarantees. They
weren't worth the paper in practice, but you may be compelled to have
them as a mortgage condition (for us it depended on the proprtion of the
purchase price they loaned us). At the time we bought, the then cellar
was considered "rough storage", so damp didn't matter (shame about the
ground floor joists!).
If you don't need the guarantees, I reckon it's one of the easiest "big"
DIY jobs I've ever done - we had two "difficult" walls (Dutch mortar,
18" thick with rubble infill), and it worked brilliantly. We did all the
injection over a week-end, including the interior walls, but the
plastering was done much later when we converted the cellar.
>
>Asher.
>
>--
>Asher Hoskins | Finally, I'll add that adding small frogs
>DoD #506 | to your coffee enhances absorption of
>PGP key available | several psychogenic tannins.
>as...@prl.philips.co.uk | --- from alt.drugs.caffeine FAQ
If you want the gory details, email me (I expect the newsgroup would be
bored stiff).
--
Simon Muir sim...@muircom.demon.co.uk
"Cricket is best described as organised loafing"
Archbishop William Temple ("Quote-Unquote" 21.5.96, R4)
Andrew Mawson
>Hello.
>
>Has anyone here ever treated a house using chemical damp course injection?
>damp problem and I was wondering how big a job it would be to put a new
>dampcourse in myself or whether I should leave it to a building preservation
>does include replastering) and I can get the necessary equipment and
>chemicals for under #500 if I do it myself so obviously there's a large
>financial incentive for doing it myself.
>
>a height of 3' above the floor there's going to be a lot of replastering
>to be done. Am I foolish to even think about doing this replastering myself?
>
>
>--
>Asher Hoskins | Finally, I'll add that adding small frogs
>DoD #506 | to your coffee enhances absorption of
>PGP key available | several psychogenic tannins.
>as...@prl.philips.co.uk | --- from alt.drugs.caffeine FAQ
Asher,
According to a feature in the Daily Telegraph recently, only 1 in 10
suposed cases of rising damp are infact rising damp. The other 9 are
from condensation on the cooler lower parts of the wall. Apparently this
was based on research from (I think) the Building Research Council. They
also stated that if a wall was already damp, the pressure used
conventionally to install the silicone fluid would not create a complete
barrier. They also said that for damp to rise the ammount normally
associated with rising damp the footings of the wall would have to be in
(from memory) 80% saturated ground, equivelent to a marsh.
Makes you think..... makes ME think having paid for silicone to be
injected into four houses over the course of several moves.
Incidently, squirting the fluid in is relatively cheap, its the labour
of drilling a suitable hole in each brick, and hacking plaster off and
re-instating that costs.On my current house I got Rentokil to squirt the
fluid and other cheaper labour to do the prep. and make good. That way I
still had a guarantee that would be worth having in a few years, but
saved money.
Good luck
Andrew Mawson ------> and...@br13jl.demon.co.uk
Bromley, Kent, UK 0181-466-5582
<-------------Happiness is a fully ticked off list------------->
Simon Muir
In article <4pr6pp$3...@bbcnews.rd.bbc.co.uk>, Matthew Marks
<mat...@rd.bbc.co.uk> said this sort of thing:
>The reason why you are supposed to remove 3' of plaster is that if the wall
>has been damp, hydroscopic salts are brought up with the damp, and these will
>keep the wall damp by absorbing moisture from the atmosphere even when the
>treatment prevents water from being drawn out of the ground. You are supposed
>to use special plaster as well, I believe.
Sounds fairly convincing, but you probably mean hygroscopic salts.
In actual fact, the effluorescence of the salts is usually what does the
damage - it makes the wall surface friable and difficult to decorate,
lifts wallpaper, and it can detatch the plaster from the render
underneath, and/or the render from the structural part of the wall. In
my very limited experience, once it's dried out, it stays dry, and you
can seal the surface nicely with a diluted PVA mix (wonderful stuff,
PVA).
For re-rendering prior to re-plastering, you put waterproofing additive
into the mix ("pore-filler"), which basically fills the microscopic
voids in the render (around the sand particles) through which the water
can pass. Taylor's book on plastering recommends a waterproof mix at
least 2' beyond any apparent dampness, which probably explains the 3'
usual practice, and two or more coats, each 9mm thick (which is all very
well, provided there's enough room behind the existing wall surface
you're feathering into!).
Taylor's useful book:
J.B.Taylor, "Plastering", George Godwin, London, 4th Edition 1985
ISBN 07114-5541-4
FWIW
--
Simon Muir sim...@muircom.demon.co.uk
nightjar
In article <Dsy36...@prl.research.philips.com>, Asher Hoskins says:
>
>I'm buying a turn of the century terrace house which has somewhat of a
>damp problem and I was wondering how big a job it would be to put a new
>dampcourse in myself or whether I should leave it to a building preservation
>company.
Unless your Building Society insists, don't bother with putting
in a DPC. Very recent research has shown that 'rising damp'
is almost never caused by moisture rising through the brickwork
and that added DPCs are a complete waste of money.
For genuine rising damp to happen the moisture content of the
soil has to be so high that you would need a mooring for a
boat to get you through the swamp :-)
The same researchers also showed that you should place very
little reliance on moisture readings taken by a surveyor. Most
are quite unaware that their moisture meters even have limitations,
much less what they are. A very high percentage of moisture
readings, particularly in brick and plaster, are inaccurate or unreliable.
You would do much better to take steps to avoid the condensation
which is almost certainly the cause of the damp problems. One
of the reasons for the rising damp myth is that the damp appears
low down on the walls. Strangely enough, heat rises, making the
upper part of the walls warmer and less liable to condensation.
Add a few air bricks to the walls and make sure that the ones you
already have are clear. If the house has been draught proofed, take
out enough of the draught proofing to restore adequate ventilation.
Nightjar
Simon Muir
In article <4pus6p$e...@s02-brighton.pavilion.co.uk>, nightjar
<nigh...@pavilion.co.uk> said this sort of thing:
>In article <Dsy36...@prl.research.philips.com>, Asher Hoskins says:
>
>Unless your Building Society insists, don't bother with putting
>in a DPC. Very recent research has shown that 'rising damp'
>is almost never caused by moisture rising through the brickwork
>and that added DPCs are a complete waste of money.
That's a very sweeping statement! A great deal depends on location and
construction methods and age. In Bristol, where I live, there's a lot of
stone construction, with Bath stone and/or dutch mortar around
sandstone/limestone blocks, rubble infill, etc. In adverse conditions,
these methods emulate blotting paper.
I know of at least two instances (my own house, and one I looked round
recently as a prospective buyer) where _rising_ damp was the problem,
and in our case fixed (12 years ago) with a chemical DPC. In the other
house, it destroyed the first floor joists and ground floor ornamental
plasterwork (and all woodwork/plaster in between that and the ground).
>
>For genuine rising damp to happen the moisture content of the
>soil has to be so high that you would need a mooring for a
>boat to get you through the swamp :-)
>
Hmmm...
>The same researchers also showed that you should place very
>little reliance on moisture readings taken by a surveyor. Most
>are quite unaware that their moisture meters even have limitations,
>much less what they are. A very high percentage of moisture
>readings, particularly in brick and plaster, are inaccurate or unreliable.
I'd agree there! "Moisture meters" are a daft idea. Start by
guaranteeing that the meter-wall interface is a constant impedance and
you might have something, otherwise it's just guesswork.
>
>You would do much better to take steps to avoid the condensation
>which is almost certainly the cause of the damp problems. One
>of the reasons for the rising damp myth is that the damp appears
>low down on the walls. Strangely enough, heat rises, making the
>upper part of the walls warmer and less liable to condensation.
>
>Add a few air bricks to the walls and make sure that the ones you
>already have are clear. If the house has been draught proofed, take
>out enough of the draught proofing to restore adequate ventilation.
>
I agree with you there too, but it's a non sequitur from the first
point.
>Nightjar
--
Simon Muir sim...@muircom.demon.co.uk
Paul Q Morrison
On 15 Jun 1996 17:34:17 GMT, nigh...@pavilion.co.uk (nightjar) wrote:
>In article <Dsy36...@prl.research.philips.com>, Asher Hoskins says:
>>
>>I'm buying a turn of the century terrace house which has somewhat of a
>>damp problem and I was wondering how big a job it would be to put a new
>>dampcourse in myself or whether I should leave it to a building preservation
>>company.
>(snip)
>
>Unless your Building Society insists, don't bother with putting
>in a DPC. Very recent research has shown that 'rising damp'
>is almost never caused by moisture rising through the brickwork
>and that added DPCs are a complete waste of money.
I would love to see this recent research you are re fairing to.
>
>For genuine rising damp to happen the moisture content of the
>soil has to be so high that you would need a mooring for a
>boat to get you through the swamp :-)
>
Cut -------
>Add a few air bricks to the walls and make sure that the ones you
>already have are clear. If the house has been draught proofed, take
>out enough of the draught proofing to restore adequate ventilation.
This is the worst advice I have ever heard. I have been in the
building game for 15 years and now work in building maintenance which
includes a lot of rising damp and I have never heard such dribble
Rising damp is caused by the break down or no DPC. If this is not
present the water in the brick will rise to the height of the water
table in the surrounding soil. The only way to cure it is to replace
the DPC by injection or other wise.
What you are referring to is condensation related moisture that will
be cured in the way you have specified.
If you could tell me the source of your information I would like to
verify.
Bye
*****************************************************************
* *
* Paul Q Morrison *
* *
* E-Mail Pau...@cqm.co.uk *
* WWW http://users.colloquium.co.uk/~paul_m/home1.htm *
* Fido Net Paul Morrison 2:259/2.5 *
* Pointing from Alba Glasgow +44.0141.880.7863/45 * *
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Matthew Marks
Simon Muir (sim...@muircom.demon.co.uk) quoted Nightjar:
: >The same researchers also showed that you should place very
: >little reliance on moisture readings taken by a surveyor. Most
: >are quite unaware that their moisture meters even have limitations,
: >much less what they are. A very high percentage of moisture
: >readings, particularly in brick and plaster, are inaccurate or unreliable.
:
: I'd agree there! "Moisture meters" are a daft idea. Start by
: guaranteeing that the meter-wall interface is a constant impedance and
: you might have something, otherwise it's just guesswork.
Well I think the difference in conductivity between dry plaster and damp
plaster must be very large. I would have thought that you could fairly
accurately the relative levels of dampness across the same wall, and that is
what is often done - in my case the surveyor predicted that there were
back-gutter problems in the himney stacks by probing the chimney breasts and he
was right.
Matthew mat...@rd.bbc.co.uk My opinions, not Auntie's.
Matthew Marks
Paul Q Morrison (Pau...@cqm.co.uk) wrote:
: Rising damp is caused by the break down or no DPC. If this is not
: present the water in the brick will rise to the height of the water
: table in the surrounding soil.
Erm, that implies that the water table is above ground level! So long as
there is damp at the base of the foundations (and that doesn't necessarily
mean that they are below the water table either - if you dig below the water
table the hole will eventually fill with water, but ground above that need not
be bone dry) and the building materials have the right characteristics, the
water will rise by capillary action.
But sorry, I'm being picky!
I think maybe this research really shows that many people are conned into
having DPCs fitted by the DPC companies or over-zealous mortgage companies,
where there is really no damp problem to begin with, or it is caused
by something else, eg condensation or penetrating damp.
Jon Rouse
Pau...@cqm.co.uk (Paul Q Morrison) wrote:
>This is the worst advice I have ever heard. I have been in the
>building game for 15 years and now work in building maintenance which
>includes a lot of rising damp and I have never heard such dribble
He may be right. I remember many years ago reading (I think in Architects
Journal) that the Building Research Station had set up a study into
rising damp. They build a structure in the dampest (waterlogged) part of
their grounds, with no dampcourse, a brick outer wall and a
plastered block inner leaf and no dpc and sat back and waited for the
damp to rise. I understand the study had to be abandoned some time later
when there was no sign of rising damp.
The other danger with a dpc in older buildings with rubble filled walls
is that before installation damp penetrates the outer leaf, and runs
harmlessly down into the ground. After installing the dpc the damp
appears at either side of the wall, causing more problems.
>Rising damp is caused by the break down or no DPC.
'Rising damp' if it exists at all, is caused by water.
>If this is not
>present the water in the brick will rise to the height of the water
>table in the surrounding soil.
>So walls above ground will be free of it?
>The only way to cure it is to replace
>the DPC by injection or other wise.
--
Personal email: J...@timewarp.demon.co.uk
Work related email: rou...@royalmail.co.uk
http://www.geocities.com/Athens/1992
Usenet comments do not necessarily reflect the views of my employer.
andy the pugh
In article <4q33sh$g...@bbcnews.rd.bbc.co.uk>, the moving finger of
mat...@rd.bbc.co.uk wrote...
>
>I think maybe this research really shows that many people are conned into
>having DPCs fitted by the DPC companies or over-zealous mortgage
companies,
As a condition of my mortgage I had to have a DPC fitted. (fortunately the
previous owners agreed to pay for it as a condition of the sale)
Strangely only one wall had to be done, and this was on the street side.
When I mention that there is a coal hatch 2' from cellar floor height onto
the pavement and the the DPC injection holes are above the heads of passers
by I think you will agree that there is something strange about the
situation.
--
ap
Paul Q Morrison
On 17 Jun 1996 08:09:53 GMT, mat...@rd.bbc.co.uk (Matthew Marks)
wrote:
>Paul Q Morrison (Pau...@cqm.co.uk) wrote:
>: Rising damp is caused by the break down or no DPC. If this is not
>: present the water in the brick will rise to the height of the water
>: table in the surrounding soil.
>
>Erm, that implies that the water table is above ground level!
Not at all, it means the house is below the water level.
i.e. if you have a loch on one side of a hill it does not mean any
water on the other is will be the same height. A river or stream for
example will take this water away but the water table in the soil will
be similar to that of the loch. You could build a house on this side
and it will be below the water table level.
> So long as
>there is damp at the base of the foundations (and that doesn't necessarily
>mean that they are below the water table either - if you dig below the water
>table the hole will eventually fill with water, but ground above that need not
>be bone dry) and the building materials have the right characteristics, the
>water will rise by capillary action.
Yes, capillary attraction can have an effect on this also.
>
>But sorry, I'm being picky!
>
>I think maybe this research really shows that many people are conned into
>having DPCs fitted by the DPC companies or over-zealous mortgage companies,
>where there is really no damp problem to begin with, or it is caused
>by something else, eg condensation or penetrating damp.
>
This is true.
Bye for now.
Matthew Marks
nightjar (nigh...@pavilion.co.uk) wrote:
:
: Unless your Building Society insists, don't bother with putting
: in a DPC. Very recent research has shown that 'rising damp'
: is almost never caused by moisture rising through the brickwork
: and that added DPCs are a complete waste of money.
: For genuine rising damp to happen the moisture content of the
: soil has to be so high that you would need a mooring for a
: boat to get you through the swamp :-)
I'm not convinced about this. My parents' previous house had very noticeable
rising damp which was cured completely by installing a chemical DPC. When I
took thy vinyl wallpaper off my dining room wall there was a clear spread of
old damp going upwards from one corner where the solid floor of the kitchen
was bridging the original DPC. Admittedly this latter problem could have been
caused by leaking pipes or faulty drains associated with the kitchen.
Matthew Marks
:
Eeek! Capillary _action_!!!
<giggle>
Other points accepted. (Including hy_g_roscopic salts earlier!)
nightjar
In article <gEyxAFAC...@muircom.demon.co.uk>, Simon Muir <sim...@muircom.demon.co.uk> says:
>
>In article <4pus6p$e...@s02-brighton.pavilion.co.uk>, nightjar
><nigh...@pavilion.co.uk> said this sort of thing:
>>in a DPC. Very recent research has shown that 'rising damp'
>>is almost never caused by moisture rising through the brickwork
>>and that added DPCs are a complete waste of money.
>
But one made by, if I recall the article correctly, the Building Research
Council based on exhaustive research.
>A great deal depends on location and
>construction methods and age.
Which is why they chose brick commons, one of the most absorbent
building materials, with a soft mortar, to test. Their claim is that other
materials will be less affected.
>
>I know of at least two instances (my own house, and one I looked round
>recently as a prospective buyer) where _rising_ damp was the problem,
(snip)
>>
>>For genuine rising damp to happen the moisture content of the
>>soil has to be so high that you would need a mooring for a
>>boat to get you through the swamp :-)
>>
I don't have the article to hand, so I cannot remember whether
they said it was 65% or 85% moisture content required for damp
to genuinely rise. I do recall the statement that the moisture level
was equivalent to the average swamp. At lower levels there
was no sign of moisture rising in the test walls.
I have no axe to grind about this. The reason I don't have the
article is that it was in a daily paper, I think The Telegraph, within
the last few weeks and it had no more than a passing interest
for me at the time. I posted it here because the research does
go against all accepted belief, which the researchers acknowledged.
You can believe it and spend a few hundred pounds on preventing
condensation, or ignore it and spend several thousand pounds on
a DPC. Since the former will probably be necessary anyway, I know
which I would try first if I had the problem.
Nightjar
Andy Mabbett
>Unless your Building Society insists, don't bother with putting
>in a DPC. Very recent research has shown that 'rising damp'
>is almost never caused by moisture rising through the brickwork
>and that added DPCs are a complete waste of money.
Whatever the truth of the above, consider the problems of selling a
house with the DPC removed.
Andy Mabbett
(personal view only - *not* my employers!)
Wookey
Andrew Mawson <and...@br13jl.demon.co.uk> wrote:
>According to a feature in the Daily Telegraph recently, only 1 in 10
>suposed cases of rising damp are infact rising damp. The other 9 are
>from condensation on the cooler lower parts of the wall.
this house (30's semi) was diagnosed as having 'some damp'. fortunately we
weren't borrowing enough of the BS that they wanted to insist on a DPC (as
is their wont). We got a number of Damp companies in, and I watched them
do their checking. The results varied wildly, from one lot who reckoned we
needed an injection DPC for all the outside & _inside_ walls. To another
lot (who did a proper check involving peeling lumps of plaster off and
seening what sort of material the wall was made from) who reckoned we
probably didn't have and rising damp to speak off, juist some penatrating
damp round windows. bits of dodgy rendering, and the render bridging the
DPC wasn't helping.
Oddly enough I was inclined to believe the last guy, especially as he was
the only one who correctly identified the construction as brick outer,
cinder block inner with cavity (everyone else had said it was solid
9"brick). He had also noted that we did have a DPC, and it seemed to be in
reasonable fettle. They recommended putting in a bell drip to stop the DPC
being bridged, and to fix the leaks.
My tests suggest that all the damp has now cleared up (and you could only
find it with a meter before), but I'll get one of the professionals in
with their meter sometime just to see what they say. I am generally of the
opinion that if it isn't _obviously_ damp (mould, cold & clammy, rot) etc,
then you don't have a problem.
So I wouldn't be suprised to find that some large proportion of rising
damp work is simply keeping DPC companies in business, and isn't really
required.
peter scott
as...@prl.philips.co.uk (Asher Hoskins) wrote:
>Hello.
>Has anyone here ever treated a house using chemical damp course injection?
> I've got a quote for about #2000 for doing the job
This sounds like quite a lot. I had a large house done a few years ago
and the cost for injection only was three hundred. It has been very
effective. This was on a mixture of brick and flint where the mortar
is lime mortar and soft, and soft red Norfolk brick. You have to put
up with small plastic plugs outside.
> Am I foolish to even think about doing this replastering myself?
No. I learned the hard way and the principles are:
1 Get a decent float
2 Mix the plaster properly. Put water into a bucket. Add the plaster
and stir. When the plaster starts to push against you stop. It will be
a lot wetter than you think it should. IT MUST BE WET. Sorry to
shout but I learned the hard way. Too dry and it will fall off.
3 Put the plaster on a board.
4 Scrape off a trowel-full.
5 Spread as evenly as you can.
6 Don't do too much before working it with a wet float to a smooth
surface.
7 If it aint perfick don't panic. You can smooth it with Polyfilla.
8 If poss find a wall that doesn't matter and waste a bag practising.
9 If you make a muck, then get a plasterer. These days this shouldn't
cost a lot.
PS Wear a mask when mixing. Sirapite is foul stuff.
Happy muscle-building!
Peter Scott
Alan J. Flavell
In article <31c45d91...@news.colloquium.co.uk>, Pau...@cqm.co.uk (Paul Q Morrison) writes:
>
>Rising damp is caused by the break down or no DPC. If this is not
>present the water in the brick will rise to the height of the water
>table in the surrounding soil.
I don't see anyone arguing with that. However, the problem is
usually with damp that's a foot or more _above_ ground level. If
the water table were a foot or more above ground level, you can
work out the consequences for yourself.
Whether you are right or not as far as principles are concerned,
I don't have the expert knowledge to be able to judge. But for
sure the argument you have presented has not brought us much further
forwards.
I would certainly be interested to hear this evidence that the
previous poster was referring to.
>What you are referring to is condensation related moisture that will
>be cured in the way you have specified.
But how can we know? The building socy's surveyor will stick his
meter somewhere on the available wall and tell us to get a DPC firm in.
A mortgage prospect isn't given the chance to try the other, low-cost,
option for a few months to see how it works out.
--
Alan
Brought to you by fully refurbished pre-owned electrons.
Martin Harriss
: >Rising damp is caused by the break down or no DPC. If this is not
: >present the water in the brick will rise to the height of the water
: >table in the surrounding soil.
Incorrect I'm afraid. A previous poster mentioned capilliary action.
I remember an experiment at school in which we placed two peices of glass
close together and managed to get water to rise up the gap between them.
This is what is happening in the wall. There are thousands of microscopic
spaces between the grains in the bricks and mortar, and moisture is induced
to rise up to three feet from ground level, collecting salts on the way, which
get left on the surface when the moisture evaporates. The evaporation itself
draws more moisture up.
The water table is not really involved, although if the soil is very well
drained, and the water table is low enough, you would probably not get
damp problems. Dig a hole in the garden until free water lies in the bottom;
then you will know where the water table is.
Andrew Gabriel
In article <4pus6p$e...@s02-brighton.pavilion.co.uk>,
nigh...@pavilion.co.uk (nightjar) writes:
>
>Unless your Building Society insists, don't bother with putting
>in a DPC. Very recent research has shown that 'rising damp'
>is almost never caused by moisture rising through the brickwork
>and that added DPCs are a complete waste of money.
A long time ago, I knew someone who worked for the Building
Research Establishment(?). He also commented that a lot of
what people think is rising damp is actually condensation.
He suggested a way to tell which you have...
Tape a large sheet of aluminium foil over the damp area for
a few days. Then take the sheet down and look at it. You will
probably have water condensation on one side and not the other.
If it was on the side facing the wall, you have rising damp.
if it was on the side facing the room, you have condensation.
I havn't actually got round to trying this out myself yet.
If anyone tries this out, perhaps they would report back the
results - if it works, it would be a good one for the FAQ.
Incidently, I suspect the sheet of foil might accelerate mould
growth on the wall, so be warned!
--
Andrew Gabriel Home: And...@cucumber.demon.co.uk
Consultant Software Engineer Work: Andrew....@net-tel.co.uk
Andy Woodward
|Tape a large sheet of aluminium foil over the damp area for
|a few days. Then take the sheet down and look at it. You will
|probably have water condensation on one side and not the other.
|If it was on the side facing the wall, you have rising damp.
|if it was on the side facing the room, you have condensation.
But if the wall is already afffected by damp no matter what the source, you'll
get condensation on the walll side of the sheet anyway, unless you can get
that wall BONE dry beforehand........
Richard Gethin
In article <azw.12633...@aber.ac.uk>, Andy Woodward
<a...@aber.ac.uk> writes
your hand along the front of the skirting board. If the front of it is
wet it is definateley condensation, or your room is under 3" of water.
--
Richard Gethin
Andrew Gabriel
In article <azw.12633...@aber.ac.uk>,
a...@aber.ac.uk (Andy Woodward) writes:
>|Tape a large sheet of aluminium foil over the damp area for
>|a few days. Then take the sheet down and look at it. You will
>|probably have water condensation on one side and not the other.
>|If it was on the side facing the wall, you have rising damp.
>|if it was on the side facing the room, you have condensation.
>
>But if the wall is already afffected by damp no matter what the source, you'll
>get condensation on the walll side of the sheet anyway, unless you can get
>that wall BONE dry beforehand........
>
I don't think so - the theory behind the test seems fairly sound to
me...
Condensation is caused by the wall being colder than the air
near it, and the air containing sufficient moisture that when
it cools due to contact with the wall, some of its moisture is
given off forming condensation.
When the sheet of foil is placed over the wall, it will settle
at a temperature somewhere between that of the wall and that
of the room air. Considering the very small amount of air trapped
between the foil and the wall, it will be heated by the warmer
foil and cooled by the cooler wall. Condensation will not form
on the wall-side of the foil as it is hotter than both the air
trapped behind it and the wall. However, the foil will be cooler
than the room air, so condensation will form on the side facing
the room.
So much for the theory, I've just stuck a piece over a damp
patch, and I'll see what happens...
Andrew Gabriel
In article <4rf0ip$n...@cucumber.demon.co.uk>,
and...@cucumber.demon.co.uk (Andrew Gabriel) writes:
>
>So much for the theory, I've just stuck a piece over a damp
>patch, and I'll see what happens...
The sticky tape came away from the wall and the foil fell off !!
andy the pugh
In article <4rhip6$n...@cucumber.demon.co.uk>, the moving finger of
and...@cucumber.demon.co.uk wrote...
>
>In article <4rf0ip$n...@cucumber.demon.co.uk>,
> and...@cucumber.demon.co.uk (Andrew Gabriel) writes:
>>
>>So much for the theory, I've just stuck a piece over a damp
>>patch, and I'll see what happens...
>
>The sticky tape came away from the wall and the foil fell off !!
>
That'll be damp then mate.
--
ap
Phil Addison
Andrew Mawson <and...@br13jl.demon.co.uk> wrote:
[snipped comments about Daily Telegraph article]
>
> Incidently, squirting the fluid in is relatively cheap, its the labour
> of drilling a suitable hole in each brick, and hacking plaster off and
> re-instating that costs.On my current house I got Rentokil to squirt the
> fluid and other cheaper labour to do the prep. and make good. That way I
> still had a guarantee that would be worth having in a few years, but
> saved money.
You're supposed to drill TWO holes in each brick to a depth to
inject at the middle of the brick. The fluid spreads out in a
sphere from the injection point and once it breaks the surface
anywhere it won't expand much further hence you make two 4.5" dia
spheres of fluid in each 9" brick. So it's holes on 4.5" centres
please. This is how you identify cowboy work (1) Holes MUCH more
than 4.5" apart, typically 9" or more, (2) brickwork not exposed
so they have no way of knowing if the holes are in the correct
place.
A major problem I found with injection is that there seem to be 3
sorts of brick (a) "Hard" ones that will not absorb the fluid
however long you pump, (b) cracked ones that allow the pressure
to escape so fluid gushes everywhere but does not get into the
core of the bricks and (c) "good" ones that take the fluid as
described above in 2 spheres.
I suggest you do a trial on a loose brick (not in the wall, that
is). Drill the 2 holes in it and inject. You should see the fluid
appearing as an expanding circle on 5 faces. Note how long it
takes to saturate the brick. My "good" bricks take about 1/2 to 2
minutes. Type (a) "bad" ones, I pumped for 30 minutes and it
never reached the surface.
BTW, I spoke to the makers of the fluid and they tell me that it
does not block the pores, but coats the inside surface of each
pore and greately reduces the surface tension so that the brickk
then will not soak up the water. Seems reasonable to me. Because
of this you CAN re-inject if the first effort was 'cowboyed'. I
thought before that you were buggered if you didn't get right
because the brick would then be cloged up - but fortunately not
so.
I'm no building expert - just an engineer - and the above is what
I found by experiment. Has anyone else thought about this?
--
Phil Addison
Bristol, England
Phil Addison
pe...@paston.co.uk (peter scott) wrote:
> as...@prl.philips.co.uk (Asher Hoskins) wrote:
> > Am I foolish to even think about doing this replastering myself?
>
> No. I learned the hard way and the principles are:
> 1 Get a decent float
> 2 Mix the plaster properly. Put water into a bucket. Add the plaster
> and stir. When the plaster starts to push against you stop. It will be
> a lot wetter than you think it should. IT MUST BE WET. Sorry to
> shout but I learned the hard way. Too dry and it will fall off.
> 3 Put the plaster on a board.
> 4 Scrape off a trowel-full.
> 5 Spread as evenly as you can.
> 6 Don't do too much before working it with a wet float to a smooth
> surface.
> 7 If it aint perfick don't panic. You can smooth it with Polyfilla.
> 8 If poss find a wall that doesn't matter and waste a bag practising.
> 9 If you make a muck, then get a plasterer. These days this shouldn't
> cost a lot.
>
> PS Wear a mask when mixing. Sirapite is foul stuff.
That's nice and clear - thanks.
I've done quite a bit of plastering in small areas, patching up
2' - 3' areas and now I'm going to have a go at a *whole* wall -
with a window in it.
I know about fixing the angled beading to give nice sharp
external corners, but would be grateful for comments on how I'm
proposing to go about it.
I've got a 4' long float, and hand floats, and am thinking of
nailing lathes say 12mm thick all around the wall internal angles
to give me a decent edge to run the float along. I was going to
use undercoat plaster - the stuff with polystyrene beads in it -
for this. When this has gone off, I thought I'd tack thin ply
strips (3mm) on top of the lathes to guide my top skim coat.
Is all this usual or do you just wack it on 'by eye' - given
enough practice of course.
What plaster types are recommended please. And are the
thicknesses I'm planning about right?
Simon Muir
In article <31dda762...@news.demon.co.uk>, Phil Addison
<ph...@severn.demon.co.uk> said this sort of thing:
>
>A major problem I found with injection is that there seem to be 3
>sorts of brick (a) "Hard" ones that will not absorb the fluid
>however long you pump, (b) cracked ones that allow the pressure
>to escape so fluid gushes everywhere but does not get into the
>core of the bricks and (c) "good" ones that take the fluid as
>described above in 2 spheres.
I've always known the type (a) you refer to as "engineering" brick, used
for damp surroundings like sewer and manhole linings. Good news:
although it doesn't take up the chemical, it doesn't take up water
either!
I believe the correct treatment is as for stonework - inject the mortar
instead.
>
>I'm no building expert - just an engineer - and the above is what
>I found by experiment. Has anyone else thought about this?
Me neither, but I did the injection OK twelve years ago -- our
purchasers' surveyor confirmed it last Tuesday!
--
Simon Muir sim...@muircom.demon.co.uk
(usual caveats, etc.)
Kevin Poole
In article: <31dda762...@news.demon.co.uk>
ph...@severn.demon.co.uk (Phil Addison) wrote:
[snipped background and good advice on drilling]
> BTW, I spoke to the makers of the fluid and they tell me that it
> does not block the pores, but coats the inside surface of each
> pore and greately reduces the surface tension so that the brickk
> then will not soak up the water. Seems reasonable to me. Because
> of this you CAN re-inject if the first effort was 'cowboyed'. I
> thought before that you were buggered if you didn't get right
> because the brick would then be cloged up - but fortunately not
> so.
>
An Estate Agent once explained to me that one particular injection
process was so good that a treated brick would float.
I could not face trying to explain, but I have often thought that
this bloke does Building Society surveys on which so much money
rests.
--
-------------------------------------------------------
Kevin Poole EMail po...@draycot.demon.co.uk
Clock Repairer Tel: 01332 872450
-------------------------------------------------------
Phil Addison
REPOST - Sorry to repost this but I think my question was missed
amidst the long thread topic which I previously posted it under.
So I'm starting a new thread.
pe...@paston.co.uk (peter scott) wrote about "Chemical Damp Proof
Courses & Plastering":
--
Phil ---- Bristol
Peter Scott
In article <31e2978d...@news.demon.co.uk>, Phil Addison
<ph...@severn.demon.co.uk> writes
>
>I've got a 4' long float, and hand floats, and am thinking of
>nailing lathes say 12mm thick all around the wall internal angles
>to give me a decent edge to run the float along. I was going to
>use undercoat plaster - the stuff with polystyrene beads in it -
>for this. When this has gone off, I thought I'd tack thin ply
>strips (3mm) on top of the lathes to guide my top skim coat.
Sounds fine to me. This is similar to the method used by people
applying stucco rendering to outside walls. The thicknesses seem
a bit high, particularly the skim coat. The key on my keyboard to
the left of 'C' has just stopped working, so I'll substitute
'?' I always use Sirapite, because you can get away with one
coat, but then I'm basically an idle so-and-so.
I think you'll need to work on the edges where the laths were. Good
old polyfilla eh?
>Is all this usual or do you just wack it on 'by eye' - given
>enough practice of course.
Yes, I'm afraid I do, but then I li?e in a old house and some
imperfections don't matter. In fact I had to force some
builders not to gi?e me a highly polished finish.
>
>What plaster types are recommended please. And are the
>thicknesses I'm planning about right?
See abo?e.
>
BTW, is there a ?irus which knocks out keys at random? I'?e
lost other keys before
>--
>Phil ---- Bristol
___________________________________________________________________
Peter Scott
pe...@lilacs.demon.co.uk
psc...@ccn.ac.uk
Was pe...@paston.co.uk
Simon Muir
In article <3E9y5EAD...@lilacs.demon.co.uk>, Peter Scott
<pe...@lilacs.demon.co.uk> said this sort of thing:
>
>BTW, is there a ?irus which knocks out keys at random? I'?e
>lost other keys before
>>--
>>Phil ---- Bristol
>
>___________________________________________________________________
>Peter Scott
>pe...@lilacs.demon.co.uk
>psc...@ccn.ac.uk
>Was pe...@paston.co.uk
I think it's localised to the Bristol area (I'm there too). The "V" has
become ery unreliable on my keyboard as well - works if I press it
carefully, but bad at normal typing speeds. You're not using an ancient
Viglen k/b are you? I've had this one for 8 years and am reluctant to
replace it 'coz it feels comfortable.
--
Simon Muir "Regional Shopping Centres --
sim...@muircom.demon.co.uk the retail equivalent of
Bristol, United Kingdom slash-and-burn agriculture"
Simon Muir
In article <31EADD...@mdx.ac.uk>, John Schmitt <Joh...@mdx.ac.uk>
said this sort of thing:
Erm, ... ackshully I didn't write it!
><stuff about non- functioning Harvey Smith key>
>You may well find that if you lever off the keycap, (I use a pair of
etc., etc.
I think your newsreader's git its attributions confused.
Best regards,
--
Simon Muir, Bristol, UK "Regional Shopping Centres" are
sim...@muircom.demon.co.uk the retail equivalent of
slash-and-burn agriculture.
John Schmitt
Simon Muir wrote:
<stuff about non- functioning Harvey Smith key>
You may well find that if you lever off the keycap, (I use a pair of
still switch cleaner into the switch underneath, and use the key a few
times it will work again. I have also repaired two NEC laptops by
dismantling the keyboard and removing the fluff from between the layers.
The symptom in this case was "phantom" letters, i.e. the keys were
producing the letters without being pressed but on an intermittent basis.
--
John Schmitt
Disclaimers Apply.
An Englishman in New York? No, an American in London.
John Schmitt
Simon Muir wrote:
>
> I think your newsreader's git its attributions confused.
My apologies, I was ably assisted by NOTscape.