Does rising damp through brickwork exist?

[JohnD]

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Hi,
I've copied the post below from a thread on Diynot.com which concerns rising damp. I know some people think it doesn't exist and i was wondering if anyone here had an opinion on the points that are raised.

However, there is one error in all this thinking, irrespective of the presence or not of a vertical wall covering, the mortar alone represents one continuous and uninterrupted material from ground to ceiling, the horizontal inter-brick mortar is in contact with the vertical mortar and as it is the same material it has the same capillary size. Imagine your house, you can place your finger on the pointing at floor level and run all the way to your roof without ever once having to cross another material, take your finger off the mortar or anything of the kind. What is it that prevents the mortar alone wicking water up from the base of the wall and saturating the bricks?

Amphibian makes a very valid point here i think, and one that i've been wondering about myself. Can anyone answer it?

I consider myself an 'RD doubter' as well, so i'd be quite happy for someone to successfully explain it.


As well as that, there is this:

http://www.palgrave-journals.com/jba/journal/v6/n1/full/jba201013a.html

If you read it, it seems Mr Ralph Burkinshaw has successfully (and surprisingly easily :? ) demonstrated damp rising through brickwork.

How has he done this when Jeff Howell couldn't, and that guy on the BBC documentary (he wasn't Howell was he?) claimed he used lots of different mortar mixes - did it never occur to him to try a lime mix?

I'm a bit puzzled as to how the debate can rage for so long only to (seemingly) be easily solved by an experiment i could've, with a bit of effort, carried out myself!

Surely there must be something a bit funny going on?

Thanks to anyone who takes the time to respond, or is it time to silently retreat?

Read more: http://www.diynot.com/forums/viewtopic.php?t=34549&start=180#ixzz20Qqrg07O

Thanks

 

[88v8]

Hmmm.

Make a cup of tea.
Take a digestive biscuit. For the purpose of the experiment, it should not be chocolate.
Dip (the technical word is 'dunk') one side of the biscuit briefly in the tea.
Observe the result.

After the successful conclusion of your experiment, eat and drink the apparatus.

Perhaps you never thought of your house as a large digestive biscuit. Many of us on this forum think of little else.

Ivor

 

[MdB]

I make no comment on the following (don't have the expertise). Interesting though.

http://www.palgrave-journals.com/jba/journal/v6/n1/full/jba201013a.html

I found the above whilst looking for another similar test (which I couldn't find) which gave the opposite results...

 

[88v8]

I disagree with the report's opening parapraph. A pier standing in water is no different to a pier standing on periodically wet ground. The only difference is that in one case the moisture supply is constant, in the other it is intermittent.
If masonry or water is permeable (Cotswold stone, red brick) it will have a wicking action, if it is not (eg blue brick) it won't. The height of the rise depends on the pore size, and thus how high a column of water the masonry can support before the weight of the water column overcomes the capillary action.
If the moisture supply is very intermittent, then feasibly the masonry will dry out between episodes of damp, and so the water column will never reach its ultimate potential height. Not this year, of course.

A digestive biscuit is not ideal to demonstrate the limits of capillary action, as although it rapidly demonstrates wicking, it will dissolve before the tea can rise to its ultimate height. For this purpose, something more robust such as a ginger nut might be better suited.

Ivor

 

[Matt Green]

--------------------------------------------------------------------------------
Hi,
I've copied the post below from a thread on Diynot.com which concerns rising damp. I know some people think it doesn't exist and i was wondering if anyone here had an opinion on the points that are raised.

I'm a bit puzzled as to how the debate can rage for so long only to (seemingly) be easily solved by an experiment i could've, with a bit of effort, carried out myself!

Surely there must be something a bit funny going on?

Thanks

Straightforward indeed!
1) Decide upon a definition of 'Rising Damp' that all interested parties agree upon.

That should do for a start. Get back to us when you get RIBA/RICS/BRE/BBA/NBA/PCA/NT/EH and the various historical societies to all agree. Then we can move to addressing evidence as to whether or not it exists (which will take a great deal less time).

In the meantime I suggest we dedicate our time to establishing whether or not a chocolate ginger nut exists. I've never seen one, but my boss swears blind he had them as a kid.

Matt.

 

[andrew gayton]

Oxborough Hall sits in a moat. whatever the time of year, only the first few courses of bricks appear to be damp; 'go figure' is a phrase that springs to mind.

 

[plasticpigeon]

I'd like to know the answer to this too as I have suspect rising damp on a small area of internal wall in my house which has no dpc. There are some that argue along scientific grounds that the capillary action of a brick wall can't support a column of water of significant height. It would be good to do some rudimentary calculations to see if this argument, just like the wall, holds any water!!! The experiment in your link would suggest that this argument is flawed or that the wall is getting wet but not via the mechanism of capillary action.

 

[Matt Green]

Rising damp is only a problem in a wall if there is something applied to the wall that you don't wish to have spoiled. Testing capillary action in brick piers and on exposed brick surfaces doesn't really address the reasons why a home owner would want to intervene. If water rises at all in brickwork it will rise further if it is prevented from evaporating from the surfaces of said brickwork.

Does water rise in plastered brick walls: yes. That can be easily proved with a hammer drill, an oven and a balance.
Is this effect ever due entirely and solely as a result of ground water from the soil rising through the brickwork with no other water source: not often at all.

IF:
capillary action = rising damp
THEN:
rising damp = true

IF:
capillary action /= rising damp
THEN:
define rising damp

IF:
rising damp = effect of capillary action solely due to ground water
AND:
rising damp /= penetrating damp
THEN
rising damp = false in 99.9% of cases

 

[Zebra]

I've sometimes wondered whether there might be such a thing as sinking damp. A very soft and porous brick wall might absorb quite a lot of water when it rains (my bricks, when submerged in water, bubble vigourously, and after only a few seconds have doubled in weight). Suppose the wall absorbed rainwater until the accumulation and weight of water caused it to sink down within the brick structure, collecting in the lower courses and looking for all the world like it rose up out of the ground.

 

[MdB]

I've sometimes wondered whether there might be such a thing as sinking damp. A very soft and porous brick wall might absorb quite a lot of water when it rains (my bricks, when submerged in water, bubble vigourously, and after only a few seconds have doubled in weight). Suppose the wall absorbed rainwater until the accumulation and weight of water caused it to sink down within the brick structure, collecting in the lower courses and looking for all the world like it rose up out of the ground.

Take a bucket and put the hose into the top. The moisture level will rise rapidly and I can guarantee that it isn't due to rising damp .

Alternatively, take a wall with a working DPM and clad either side with cement. Now pour in water at the top with a leaky drain pipe or similar. In this case the wall could be wetter above the DPM than below it and I seem to remember somebody talking about this situation here some years back.

 

[Zebra]

Yes I can see what you mean, in those circumstances certainly the wall could be wetter above the dpc than below it, but suppose there was a wall with no DPM and no cement render, i.e. no container for the water, just the porosity of the spongy bricks themselves, I was just wondering if the wall might be capable of holding water in that way, and that the moisture might gather in the lower courses faster than it can evaporate. Was just musing, anyway.

 

[MdB]

Yes I can see what you mean, in those circumstances certainly the wall could be wetter above the dpc than below it, but suppose there was a wall with no DPM and no cement render, i.e. no container for the water, just the porosity of the spongy bricks themselves, I was just wondering if the wall might be capable of holding water in that way, and that the moisture might gather in the lower courses faster than it can evaporate. Was just musing, anyway.

My understanding would be that the answer is yes. Whether or not you call it rising damp is debatable but the wall would still be damp.

 

[robgil]

In all gfairness DIYNOT.COM is not somewhere I would be looking for advice on old propertys, really , do a search for lime. Espacially in the plastering section. Some of the advice on there is sacrilege and a lot of the 'trades men' on there shouldnt be let within ten mile of a house built before 1970.

 

[NT]

IIRC BRE's experiments with walls in standing water could only get any rising damp to occur with a sandy lime mortar mix.

There are other reasons walls can get damper near the ground, such as condensation, rain splash, shade, less air movement etc.

NT