keyplayer said: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.
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.keyplayer said:For surface water yes, but I'm thinking of seepage through the soil.
Softus said: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 said: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.
anobium said: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
Not too simplistic - I think you've distilled the points superbly.drspock said:Is it me or am I being to simplistic in my conclusions.
It comes down to the definition of a "wall", and this is where there's a risk of oversimplification.drspock said: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...
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.drspock said:...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.
Not in brickwork it won't! Unless you have a practical example of it happening?!drspock said: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!
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.drspock said:Just a final thought , if can you accept rising damp via the plaster, why is it not possible to accept it through the bricks?
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
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
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