No Such Thing ....

[plumbers mate]

Discussion on Radio 4 at unchtime today (thursday) [You and Yours?] on whether rising damp exists or not - guess what the man from the Surveyors and the Damp proofing men were saying ......
Is the chap who wrote the book "No such thing as rising damp" one this group? If so, well done and all that.
I suppose that the programme will beon the Beeb's Listen Again page on the Web?

(Always preview -- otherwise this would have gone with the double "e" in Beeb typed as double "o"........ )

 

[jocelyn plummer]

Ooooh, shush shush, who knows. Have a look at the latest edition of Period House, it's very illuminating.

 

[Penners]

Well, as I've said before in another thread, if there's no such thing as rising damp then I'd like to know what it is that's crept up our study wall. All I know for sure is that it's damp... and it's rising.

 

[Moo]

Wash your mouth out with soap, young man. Strange things may happen in Suffolk, but that doesn't necessarily mean that they happen in the real world as well.

 

[DaveBrigg]

We have hovering damp in the dining room. The base of the wall looks and feels dry. The top of the wall looks and feels dry, but there is a damp band running about 4ft above the floor, for as long as the other side of it is external. There are no downpipes nearby, and the problem seems to have got worse since the cement render was removed from the outside. The outside face of the wall is brick, but the inside may be timber framed with brick infill. Any ideas?

(the skirting is not attached yet)

 

[jocelyn plummer]

Probably water trapped in there from before the cement render was removed. I am absolutely no expert but did have a similar nasty experience a few years ago. The local builder suggested removing the interior plaster to expose the old timbers and original bricks and let the area dry out .He was proved right, it worked.

The damp had travelled from a nearby blocked down pipe from next door. It was all sorted in about 3 months and replastered.

 

[Penners]

Strange things may happen in Suffolk

You're right, of course, Moo. It's a case of NFS.

 

[middi]

Rising damp explained. ( surely all you learned folks do not need a b****y foreigner to explain).

If I (you) live in a property built out of porous substrate material right down to the base of any foundation which the house happens to to be built on is susceptible to moisture in the ground to work its way up the wall. If the balance between moisture present and rate of evaporation is umbalanced, in favour of moisture, then the wall will show signs of damp.

Let us assume, you (I), have gone on holiday and gorgot to switch the garden hose off which was "parked" at the base of our normally dry porous base wall, the first serious conversation that takes place after two weeks or so will be something like this :-

" You left the B****Y hose pipe on !!!!!!!)"
--
" OHHhhh flipping heck, the b****y damp has risen up our lounge wall and all the wallpaper is now BUg***ed and is all your fault" . ( husband says nothing and goes down the pub)

If I (you) substituted the hose for a naturally occurring "semi"disaster such as badly drained soils , leaking gutters, broken pipes etc.., etc.., damp WILL be rising up the wall. The only damp that does not rise up the wall is "dry" damp.

 

[MdB]

damp WILL be rising up the wall.

I don't think anyone doubts this. The question is how far will it rise up the wall? I've seen a couple of reports now (wish I could find a link) where people have built test walls in troughs of water. This has shown rising damp to around 200mm from the water level if I remember correctly. This is normally below internal floor level in most houses.

Others claim that rising damp can go 1 or 2m though I personally doubt this. I will gladly be proved wrong but I would like to see some sort of experiment which proves it. Penners has a nice(?) damp patch which doesn't have an obvious cause apart from rising damp which does confuse me.

 

[middi]

It is extremely difficult to quantify how far up the wall rising damp will reach, it all depends upon the amount of " wetness" present, the porousity ( or capillary action) of the walls and rate of evaporation. Given the rate of " symbiotic unbalance " of the above one has to assume that in theory, or practice , rising damp will reach as far as the roof rafters in ideal conditions.

 

[middi]

......also damp " spores" will easily penetrate a one foot thick cement barrier in extreme condition, this eventually makes the condition worse by trapping further moisture from below and above.

 

[Penners]

Penners has a nice(?) damp patch which doesn't have an obvious cause apart from rising damp which does confuse me.

Nice, eh? For you, maybe ('cos it's not yours)! :wink:

My "nice" damp patch rises roughly 70cm up the wall.

 

[Flyfisher]

I've seen a couple of reports now (wish I could find a link) where people have built test walls in troughs of water. This has shown rising damp to around 200mm from the water level if I remember correctly.

Jeff Howell's "The Rising Damp Myth" describes his experiments with building walls in water trough as a precursor to a proposed set of student investigations into the effectiveness of various types of DPCs. The DPC experiments were cancelled when he couldn't induce any rising damp in the test walls, something that spurred him on to investigate 'rising damp' in general before concluding that it's largely a myth.

One interesting thing he describes is how the ground underneath a building will actually draw out any water from brickwork unless the ground itself is saturated, which is very unlikely unless there's an underground stream or a mains water leak involved (not unheard of apparently).

It's all rather confusing!

Meanwhile, I'm just back from a couple of weeks in Cornwall and the granite cottage we rented certainly had some damp problems. One particular granite block in the bedroom was very noticeably damp, which surprised me as I had assumed granite was pretty impervious to water. I suspect the root of this particular problem was the outside ground level, but it still surprised me as it was only one particular granite block. Perhaps granite porosity is very variable?

 

[Lime]

I have never carried out an experiment to show whether rising damp is an actualitée.
However my logic tells me that if a person wrote a book based on their experiments to mimic rising damp then anyone wishing to dispute or refute the claims could do the same.
Has anyone seen or heard of an experiment showing rising damp is a reality?
I haven't so I'm rather inclined to believe that it doesn't happen.

I'm much more convinced by the wet sponge theory on the side of the bath.
Take a soaking wet sponge out of the water and place it on a flat impermeable surface.
What happens to the water in the sponge after a while?
...when the water stops running out of the sponge any water remaining is at the bottom of the sponge.
......The top can become quite dry but the bottom will remain waterlogged for some time until it all dries out.

The same almost certainly happens in any porous substance including brick.

To confirm the theory place three wet sponges one upon another.
Evenually the bottom sponge is the only one that is wet.

So if a brick wall is damp around it's base the water has entered it somewhere else other than "risen" from below.
The water has settled to the base of the brick, often stopped from going any further by a DPC!

IMO this covers most examples of damp that I have ever experienced.
...So of course the subsoil and surroundings of the damp wall are going to be damp ... that is where the water is escaping to... if it can.

 

[Moo]

What a brilliant idea!
I was so entranced with the argument that I went rushing upstairs to share it with my OH. But he then started a 'yes, but' about capillary action and how it is affected by the spaces between particles. Apparently, the smaller the spaces, the greater the capillary action.
So I suppose we must now ask you for more detail about the type of sponge you have in mind.

 

[Nemesis]

http://www.defence-estates.mod.uk/publications/historic_buildings/historic_buildings/PDF_8111/Technical%208%2001.pdf

http://www.handr.co.uk/literature/rising_damp.htm


http://www.ridoutassociates.co.uk/services.htm


http://www.historic-scotland.gov.uk/informguide-damp.pdf


http://www.oxleyconservation.com/oxley_conservation/profiles.htm#richard

 

[Lime]

What a brilliant idea!
I was so entranced with the argument that I went rushing upstairs to share it with my OH. But he then started a 'yes, but' about capillary action and how it is affected by the spaces between particles. Apparently, the smaller the spaces, the greater the capillary action.
So I suppose we must now ask you for more detail about the type of sponge you have in mind.

Yes the blinding by science with the use of words often avoids the reality.

I don't think the capillary action argument holds any water (sorry couldn't resist it) because a pile of wet bricks after a short time only has wet bricks at the bottom.

As I said I have never seen any experiments showing rising damp exists (except for a very marginal dampening of 200mm or so) in a testbed of brickwork.

All the "learned" contibutions about rising damp I have read so far are all based on the assumption that water can rise through brick a great distance by capillary action.
Yet no experiment has ever been made to show water does anything of the sort .. even with salts and other chemicals dissolved within it.

So while there is no real acceptance that capillary action through brick does not happen (anywhere in the building business) nothing much will change as to how to deal with damp.

Capillary action in brick, except in the minds of those desperate to explain something they don't understand or for those making money out of it, doesn't exist in the way necessary to make walls really wet nor is it able to convey water upwards through brick further than a few inches.
(Yes, I know plants can transport water upwards for great distances but that is not just by capillary action is it?)

Any water in brickwork settles out and collects at the bottom ... so it appears the water has entered from below.... but that is NOT evidence of rising damp.

 

[Flyfisher]

I suspect a sponge doesn't have sufficient (any?) capilliary action to be a useful analogy for brickwork. Capilliary action will certainly draw tea to the top of a sugar lump when just a corner is dipped into the cup. If I had a box of sugar lumps I would make a small stack of them in a saucer and then add water to see how high it would be drawn.

But I do agree with Lime's point about demonstrating 'rising damp'. If it really does exist then it should be a simple matter for the damp-proofing industry to conduct a suitable demonstration to prove it once and for all. Given the incredible PR effect this would have for their industry it's rather surprising they haven't already done it.

I really don't want to sound like Jeff Howell's advertising agent but one other thing he describes in his book is how damp-proofing firms typically react when all their DPC work make no difference to the problem and the property owner seeks rectification under the guarantee. They will not accept any results from 'damp meters', insisting that the only true method is to take a core sample for lab analysis. Surprise surprise, this will usually show the wall is actually dry, which they then use to support the 'fact' that their original DPC work has been successful and any dampness on the wall must be due to condensation . . . .

 

[Lime]

I suspect a sponge doesn't have sufficient (any?) capilliary action to be a useful analogy for brickwork. Capilliary action will certainly draw tea to the top of a sugar lump when just a corner is dipped into the cup. If I had a box of sugar lumps I would make a small stack of them in a saucer and then add water to see how high it would be drawn.

I believe a sponge does have a form of capillary action otherwise it would not be able to pick up water.
Also substitute the pumice in the bath for the sponge and the result is just the same.

As for sugar that is another thing entirely.
While capillary action starts the process of mixing the two (solid and liquid) the process of dissolving soon takes over.
A completely solid whole crystal of sugar (or something else similarly soluble like copper sulphate) will absorb tea (water) as the liquid invades the crystal structure prior to sugar molecules occupying the spaces between the water molecules (dissolving)
Years ago, I experimented with a complete pack of sugar cubes and it may surprise you to know that the bottom layers of sugar cubes dissolve long before any of the upper cubes become damp.
It also makes a dreadful mess all over the table.
Perhaps those who are blessed with no children (i.e. that have any sugar cubes left) can experiment and let us know.
Unfortunately, apart from holiday adventures, I'm now a castor sugar man myself so can no longer perform such tests.

Given the incredible PR effect this would have for their industry it's rather surprising they haven't already done it.

.

I believe it has.... It must have been.. but it disproved the theory of rising damp.

 

[Penners]

capillary action and how it is affected by the spaces between particles. Apparently, the smaller the spaces, the greater the capillary action.

I agree with Mr Moo. Sponges have big 'oles. Capillary action defies gravity best when there are small 'uns (such as one might find in a porous brick).

From my own experience, I have no doubt whatsoever of the existence of rising damp. But I think the type of bricks is an important factor. Engineering bricks, for example, probably exhibit very little water absorption/capillary action, whereas soft reds probably exhibit a considerable amount.