Rising damp does not exist

[Softus]

Would it not be more natural for the water to flow around the building, under the force of gravity, than to rise through the brickwork by capillary action?

 

[keyplayer]

For surface water yes, but I'm thinking of seepage through the soil.

 

[jbonding]

Here's an idea (and I admit a fairly ill thought out one, but bear with me) -

Konrads photos of his experiments with rising damp would appear to rule out the possibility of capillary action causing moisture to rise up through brickwork. However, there is a situation I can imagine that the experiments wouldn't cover. Try to picture this:-

A property is built halfway up (or down) a hill. The soil is eg 1 metre thick throughout the gradient, and below this is an impermeable bedrock. The top of the hill receives very heavy rainfall, and this seeps down the hill. Now, imagine saturation point of the soil is reached at the property, but rain continues at the top of the hill.

Is it now possible that moisture could be forced up through the brickwork including the mortar? Not by capillary action granted, but by the water trying to find it's own level.

would it not travel through to the other side first

 

[Softus]

For surface water yes, but I'm thinking of seepage through the soil.

OK. Intuitively, your hypothesis is full of holes (pun intended), but since I have no scientific grounds for disagreeing with you, lets say that I accept it as being correct.

So that's the theory - do you have a real life practical example where this has happened? After all - reality is what this topic was intended to be about...

 

[keyplayer]

do you have a real life practical example where this has happened? After all - reality is what this topic was intended to be about...

No, this is purely speculative, and I apologise for going (slightly) off topic. But for sake of argument, if we assume that

a) Konrad is correct and capillary action between bricks and mortar is impossible (and I have to say that he has convinced me of this) and

b) rising damp exists

then we have to assume that the RD is caused by some sort of upward pressure in the ground water, the existence of which could be caused by my hypothetical situation. (Which of course assumes no other factors such as plaster bridges are to blame)

 

[Softus]

OK, I get you now. Apology not necessary, but accepted of course

Regarding the upward pressure scenario, this is a non-scenario simply because rising damp does not exist in brickwork (please see topic title).

I appreciate that you're trying to broaden the discussion, and that this is for the common good, but I really do think that inventing an hypothesis, whilst being a good way of stretching the imagination, is not valid when the premise on which it rests is itself flawed.

 

[keyplayer]

I agree.

 

[Softus]

Well that's no fun

 

[ModernMaterials]

Here's an idea (and I admit a fairly ill thought out one, but bear with me) -

Konrads photos of his experiments with rising damp would appear to rule out the possibility of capillary action causing moisture to rise up through brickwork. However, there is a situation I can imagine that the experiments wouldn't cover. Try to picture this:-

A property is built halfway up (or down) a hill. The soil is eg 1 metre thick throughout the gradient, and below this is an impermeable bedrock. The top of the hill receives very heavy rainfall, and this seeps down the hill. Now, imagine saturation point of the soil is reached at the property, but rain continues at the top of the hill.

Is it now possible that moisture could be forced up through the brickwork including the mortar? Not by capillary action granted, but by the water trying to find it's own level.

(still keeping an open mind)

firstly, conrad hasnt claimed, as far as i know, to have used every possible combination of brick/mortar-mix in his experiments and until he does he wont have ruled out the possibility of the existence of rising damp through capillary action.

secondly (the house on haunted hill) do not confuse field capacity with flooding. half way up a hill is not a bad plot if its drained correctly and even if it isnt, water is bound to flow round it somehow.

still havent seen rising damp by the way, have seen penetrative tho and condensation and plaster bridging (why cant they just cut it off?) and crap in cavity walls all of which get mislabelled

still cant get my head round hygroscopics salts and the remedy thereof

 

[Softus]

Good post MM.

Pretty please, as a small but significant courtesy, could everyone take care to spell Konrad's name correctly?

 

[drspock]

Softus, this is definitely my final post on this subject, and I do not require, or will respond to any questions on the whys and werefores of the property, or what day ,time or month it was , or even the thickness of the walls , or what planet it was on .
You will just have to read and come to your own conclusions.

I was asked to try and identify the cause of a damp problem at a large detached property, which was about 75 years old.
The dampness was evident at the base of three walls and the surface readings using a resistance meter showed that it diminished about 600 up from the solid floor level.
I explained to the owner that in order to identify what the cause of the dampness was , that I would need to carry out further tests which would involve taking samples of the wall materials.
He gave me permission and I proceeded to take samples of the plaster, mortar , and masonry, above the dpc level
The readings taken on site using a carbide meter showed that the samples of plaster at skirting board level had the highest moisture content, around 12% with the bricks and mortar samples being quite dry, ie less that 5%
I then asked for permission to remove some of the skirting boards to investigate further.
This quickly revealed that the wallplaster had been applied down and below the horizontal dpc , resulting in the moisture being drawn up the wall by the plaster.
I recomended to the owner that he should instruct his builders to remove the skirtings and cut back the plaster to a point approx 100 mm above the dpc level.
This was duely done and within a matter of weeks the dampness dissipated.
This in my opinion is just another example that there is such a thing as rising damp, and that whilst in this case it was not due to a defective dpc , it shows that the only thing holding back the capillary movement of moisture up the wall was the damp proof course.

good hunting

As a relative newcomer to this site my attention has been drawn to this long running debate and I have come to the following conclusion.
I am a layman in this field and I will stand corrected. However here goes, Anobium in his last post gave an example which initially did not make sense to me.
After giving it some thought I have come to the conclusion that what he was trying to say , was that dampness drawn up the wall via the plaster , from below the dpc, proves that, (a) dampness can rise up a wall through capillary action, and (b) the fact that the brickwork was wetter below the dpc, proves that a dpc is effective in preventing the up ward movement of moisture, ie rising damp.
If we accept this , then surely it is logical to accept that if the dpc is damaged for whatever reason then dampness will occur higher up the wall due to capillarity and that is rising damp!
Is it me or am I being to simplistic in my conclusions.
Just a final thought , if can you accept rising damp via the plaster, why is it not possible to accept it through the bricks?.

 

[Softus]

I'll answer your posts out of sequence, if I may...

Is it me or am I being to simplistic in my conclusions.

Not too simplistic - I think you've distilled the points superbly.

After giving it some thought I have come to the conclusion that what he was trying to say , was that dampness drawn up the wall via the plaster , from below the dpc, proves that, (a) dampness can rise up a wall through capillary action...

It comes down to the definition of a "wall", and this is where there's a risk of oversimplification.

I deliberately used the term "brickwork" in the first post, to distinguish from the wall 'coating', which can be inside or outside, plaster, render, plasterboard, paint, something else, or just nothing. A "wall" is therefore an assembly of components, and one VERY important concept is that water can rise between plaster and brickwork, as well as the generally agreed ability for it to rise within plaster.

...and (b) the fact that the brickwork was wetter below the dpc, proves that a dpc is effective in preventing the up ward movement of moisture, ie rising damp.

Nope - I fundamentally disagree. In anobium's scenario, which he thoroughly obscured until right at the last moment, the water rose in the plaster, and no DPC would prevent such a rise, even if the plaster had not bridged the DPC, which it did.

If we accept this , then surely it is logical to accept that if the dpc is damaged for whatever reason then dampness will occur higher up the wall due to capillarity and that is rising damp!

Not in brickwork it won't! Unless you have a practical example of it happening?!

Just a final thought , if can you accept rising damp via the plaster, why is it not possible to accept it through the bricks?

Firstly, I have never said that it doesn't rise in a brick, or bricks, only that it doesn't rise in brickwork, i.e. a masonry wall constructed from bricks and mortar.
Secondly, it is possible to accept that it occurs in brickwork - jeepers, why do I have to keep writing this? I openly postulated the non-existence of rising damp through brickwork as a deliberate and self-declared device to get people who have seen it, with their own eyeballs in their own eye sockets, in their own heads, on top of their own necks, to post information about it. Is first hand experience an unreasonable thing for me to seek? (Getting worked up - must calm down - cool wet grass...cool wet grass...)

So far, TexMex gave a good description, and explanation, but remained unsure himself. joe-90 gave a, well, um, er, er, er - well you tell me what he gave. Then anobium gave a blurred description, then stayed tight-lipped while going on a wild goose chase, and then, eventually, revealed that he was talking about a DPC breach!

I say again -

What more can a man do? You won't find anyone more open-minded than me (and JF Kennedy ), so why do you think that I won't accept RD if someone shows that it happens? Do you not find it utterly astonishing that someone in the trade of curing RD doesn't post here and explain what's going on? Am I that much of a Rottweiler that fear overcomes reason?

 

[horndean]

softus, i have spent a long too long but entertaining time reading this thread, and while konrad is pretty much the lime evangelist i would agree with much he says especially about the insulation fashionistas, but everyone seems to get hardened into their own opinion and see the evidence or interpret things the way they want to. to business. the dwarf wall photo to me seems to show a uniformly paler course of bricks above the dpc but it might be argued that the moisture - wall sitting in perpetual wetness? or seasonal?- has tracked up 30yrs of dust, cobwebs and general detritus on the bricks surface till reaching the membrane. but anobiums last case at the richenbach falls has more evidence for migration through brickwork since regardless of whether the plaster breached the dpc it still has to be picking the moisture up from the brickwork does it not? and assuming the oversite must be a foot or so below the finished floor and also one would suppose the bottom of the plaster, then the damp must originally have had to rise within that brickwork from ground level to be able to pass across to the plaster. the oversite level and ground saturation / flooding level would be useful to know, but damp rises to a maximum height in walls over a long timescale does it not?, and though porosity coefficients of brick and mortar differ significantlywhen first laid, with time intuitively (unwise?!) they may promote capillary action more readily as salts fur up the mortar, although possibly also giving rise to surface bridging across mortar joints - would this count in your defintion though softus!?, (konrad, how long have your experiments been running? - and has the rise level increased at all, evaporation conditions remaining the same?) . omigod its 2.30 am. good night and happy easter.

 

[drspock]

but anobiums last case at the richenbach falls has more evidence for migration through brickwork since regardless of whether the plaster breached the dpc it still has to be picking the moisture up from the brickwork does it not? and assuming the oversite must be a foot or so below the finished floor and also one would suppose the bottom of the plaster, then the damp must originally have had to rise within that brickwork from ground level to be able to pass across to the plaster. the oversite level and ground saturation / flooding level

Horndean, thats exactly the conclusion that I came to,and what I was trying to get across to Softus.
For whatever reason he failed to see my point .
From what I read of anobiums example he had proved that the damp course was stopping the upward movement of moisture because his tests had shown that the brickwork was considerably wetter immediately above the dpc than below.
He wasn't trying to say that a dpc would prevent moisture rising in the plaster if it was bridging the dpc , he was saying if the plaster had not bridged the dpc , there would have been no dampness because the brickwork to which the plaster was adhering to was dry.
Therefore the dpc was instrumental in stopping dampness rising above the point where the it was installed and if you accept this , you have got to accept that you can have rising damp, if, for whatever reason a damp course fails.

 

[drspock]

From what I read of anobiums example he had proved that the damp course was stopping the upward movement of moisture because his tests had shown that the brickwork was considerably wetter immediately above the dpc than below

Correction to above , should read, " brickwork was considerably wetter below the dpc than above".