Rising damp does not exist

[Softus]

If water 'soaks in', is there not every chance of it moving up through the fine 'pores' in a capillary action if the base of the material is partially immersed ?

I don't know empip - is there a chance? After all, anything is possible!

However, my assertion is that it doesn't happen, and hasn't happened - water doesn't rise through brickwork.

I'm waiting for someone to tell me I'm wrong, not for someone to tell me that I will be wrong when it happens.

I once lived in an area plagued with 'springs' appearing in cellars without warning .. not mine thankfully, but what effect would running (replenishing) water have at foundation level in the event of none or damaged DPC?

Simple - it will make the floor very wet. And, if there's a gap of the right size between the plaster inside, or render outside, and the wall, then it will rise up the surface of the wall by capillary action. And if the water in the room makes the air damp to the point where it can condense at a higher level, then it will make the wall damp at that higher level.

FYI my post didn't limit my intended debate to the injection of sealer - if you have an example of the installation of a slate, grantite, or even a green flipping kryptonite DPC into a wall, that has cured a damp problem, then I'd like to hear about it.

Surely someone does? Tick tock...

 

[TexMex]

I hope I'm safe in assuming that the problem arose sometime after the house was built, i.e. that it was dry and habitable until something happened to make it damp.

I think your assumption would be wrong. I suspect that these properties suffered from this damp from the day they were constructed. When they were new though, the flooring wouldn't yet, have been rotten. Victorian tenants would have also been more accepting of a bit of dampness in the walls, than modern owner/occupiers.

I also found some original air bricks, at the front of the houses, that had been obscured by the steps (leading up to the front door). Strangely enough, these steps seemed to have been constructed as part of the original fabric of the building. So although this was exacerbating the problem, It wasn't something that had happened recently.

do you know what happened to cause the problem?

The problem just became more of an issue due to the rotting of the flooring. You'll recall, that even my modern day client just wanted the mould covering up! He didn't actually realise there was a problem of damp. He thought it was just a bad case of condensation.

Was the party wall original, or had something been built onto

Totally original, apart from some holes that had been drilled for some kind of injection system (that obviously hadn't worked).

Also, I haven't quite understood what you did to remedy the problem

The final solution that I carried out was providing temporary support (by means of rebar through the wall and supported both sides). A course of brickwork along the entire length of the wall was then removed. A new DPC was laid in place (overlapping the DPC that was already present in front and back external walls). Finally the removed brickwork was made good with new bricks. I also added some more airbricks at the front of the houses.

It turned out to be one hell of a job. The neighbours had fairly new flooring and a fitted kitchen that they didn't want removed, so I spent a good deal of time crawling around under their floor boards. Fortunately there was a space of about four foot between the flooring and the oversite (which makes the extent of the rising damp even more impressive).

Brickwork does, indeed, soak up water like a sponge. The pace of the water through the brickwork is something of a snails pace though. Hence even solid external brickwalls don't get thoroughly soaked through even in rather sustained rainfall. But brickwork planted in wet conditions will draw the water up slowly but surely to some pretty impressive heights. The extent to which the water will rise is determined by the point where evaporation and capillary action is in equilibrium.

If previously lime rendered walls are replastered with sand/cement, this can cause the damp to rise even further (due to the reduction of evaporation through the render). Blocking of airbricks can also have a similar effect.

 

[TexMex]

However, my assertion is that it doesn't happen, and hasn't happened - water doesn't rise through brickwork.

Get yourself a roasting dish, place about half a pint of water into it. (should only be about a centimeter deep), then put a single dry brick into the the middle. Watch for about 20 minutes. You'll notice the brick gets wet, and the water in the dish dissappears. Honest, is does, just try it.

 

[Thermo]

However, my assertion is that it doesn't happen, and hasn't happened - water doesn't rise through brickwork

never laid a dry stock brick in mortar and watched what happens then!

ever taken a hammer to a sodden brick thats been in the ground a few years and seen how its soaking wet and crumbles?

 

[sidecar_jon]

empip.. oh that interesting indeed. Granite "rots" indeed it "rots" to form china clay eventualy (and sand for the beech). There are different grades of Granite though. Our house was built in 1800 and apparently cost apoximately £80 to build... and that made it fairly "posh" the cob ones being £40. It dos'nt seem to be damp and indeed there is no apparent DPC. Or anyway to put one in. I gues if its working ok just leave it.....


And yes ive seen ordinary house bricks get wet and disintigrate (thro damp and the action of frost)

 

[Softus]

I could hug you TM - finally someone (you) has written something that can be reasoned and debated.

I hope I'm safe in assuming that the problem arose sometime after the house was built, i.e. that it was dry and habitable until something happened to make it damp.

I think your assumption would be wrong. I suspect that these properties suffered from this damp from the day they were constructed. When they were new though, the flooring wouldn't yet, have been rotten. Victorian tenants would have also been more accepting of a bit of dampness in the walls, than modern owner/occupiers.

All good points, and I believe that you're right.

I also found some original air bricks, at the front of the houses, that had been obscured by the steps (leading up to the front door). Strangely enough, these steps seemed to have been constructed as part of the original fabric of the building. So although this was exacerbating the problem, It wasn't something that had happened recently.

Hmm.

do you know what happened to cause the problem?

The problem just became more of an issue due to the rotting of the flooring. You'll recall, that even my modern day client just wanted the mould covering up! He didn't actually realise there was a problem of damp. He thought it was just a bad case of condensation.

Was the party wall original, or had something been built onto

Totally original, apart from some holes that had been drilled for some kind of injection system (that obviously hadn't worked).

I'm notching up those reported failures in injected DPCs!

The final solution that I carried out was providing temporary support (by means of rebar through the wall and supported both sides). A course of brickwork along the entire length of the wall was then removed. A new DPC was laid in place (overlapping the DPC that was already present in front and back external walls). Finally the removed brickwork was made good with new bricks. I also added some more airbricks at the front of the houses.

It turned out to be one hell of a job. The neighbours had fairly new flooring and a fitted kitchen that they didn't want removed, so I spent a good deal of time crawling around under their floor boards. Fortunately there was a space of about four foot between the flooring and the oversite (which makes the extent of the rising damp even more impressive).

I'm impressed, which doesn't happen often.

The interesting part here, for me, is that you provided a DPC (membrane? presumably?) that overlapped the DPC in the walls. This is the nub of present-day regulations, although without looking it up I can't remember how explicitly they state the purpose of doing this. My own understanding of the purpose to provide a continuous layer that moisture can't breach - the role of the DPC in the wall is, I would reason, less important in preventing moisture rising through the bricks and more important in preventing wicking between the bricks and their covering.

Brickwork does, indeed, soak up water like a sponge. The pace of the water through the brickwork is something of a snails pace though. Hence even solid external brickwalls don't get thoroughly soaked through even in rather sustained rainfall. But brickwork planted in wet conditions will draw the water up slowly but surely to some pretty impressive heights. The extent to which the water will rise is determined by the point where evaporation and capillary action is in equilibrium.

The last bit makes sense, but what do you call pretty a impressive height? And without meaning to denegrate your good character, can I press you on this next point: have you actually seen an example of water having risen to an impressive height simply because the bottom of the wall was immersed in the equivalent of a roasting dish full of water?

And another thing: this idea of a brick being like a sponge is a bit too easy for me, and the definition much too woolly. Margaret Thatcher and John Major were both Tories in the same era, and they were clearly not the same kind of Prime Minister. Similarly, a brick and a sponge both have pores, and yet, clearly, a brick is not a sponge.

Moreover, do those pores in a brick connect in the same way as in a sponge? I'm not convinced that they do. Even if they did, here's a question: if you took two sponges, one on top of the other, and separated them with a layer of morter, and if the bottom one was sodden, how long would it take for the top sponge to be equally sodden?

Do you see my point?

If previously lime rendered walls are replastered with sand/cement, this can cause the damp to rise even further (due to the reduction of evaporation through the render). Blocking of airbricks can also have a similar effect.

Makes sense (the different materials having different effects on evaporation), but, once again, can you say how far you've seen it rise?

 

[Softus]

And here's an interesting entry on the RICS web site:

http://www.rics.org/Builtenvironmen...moisture_measurement_in_masonry_19950901.html

 

[TexMex]

I'm notching up those reported failures in injected DPCs!

I know absolutely nothing about the injected DPC systems. The only dealings I have had is providing alternative solutions where they have "failed". For all I know, the vast majority of these treatments work quite effectively. I just haven't seen a working example, yet.

My own understanding of the purpose to provide a continuous layer that moisture can't breach - the role of the DPC in the wall is, I would reason, less important in preventing moisture rising through the bricks and more important in preventing wicking between the bricks and their covering.

Dependant on the mix, dry mortar can be just as absorbent as the bricks themselves. In fact, it is standard practice to use a mortar with approximately the same absorption as the bricks. Therefore above DPC with standard bricks a fairly week mix (5:1 - 6:1) is the norm, whereas below the dpc, nowadays it's standard practice to use engineering grade bricks (such as staffordshire blues). These are much less absobent than stocks, and are laid with a much less permiable mortar (such as 3:1). Footings laid like this are almost as good as a DPC for preventing the rise of the water.

what do you call pretty a impressive height? And without meaning to denegrate your good character, can I press you on this next point: have you actually seen an example of water having risen to an impressive height

The job to which I previously refered, had a space of about 4ft below the floor, the thickness of the floor itself was about another 9" (allowing for the joists), and while I was there, the wall was dripping wet upto a hight of about 2.5 ft above this. That makes at least 7ft rise from the base of the wall. The oversite itself, although generally damp, had no standing water at all. There was also considerable staining of the walls that tallied with the neighbours claims of 5ft above ground level during the winter, that would be a total rise of, going on 10ft!

Moreover, do those pores in a brick connect in the same way as in a sponge? I'm not convinced that they do. Even if they did, here's a question: if you took two sponges, one on top of the other, and separated them with a layer of morter, and if the bottom one was sodden, how long would it take for the top sponge to be equally sodden?

There are a few problems with the sponge analogy. First of all, sponges tend to have much larger pores than bricks. This makes them less efficient than bricks when it comes to capillary action. To get sponges to work well you need to squeeze the air out of them and allow the partial vacuum to suck the water in. Sponges are also far softer than bricks. As a result, any water in them will cause them to deform (therefore squeezing the water out of the lower parts of the sponge). Bricks do not suffer from this, so even when the water has risen to impressive heights, it still doesn't squeeze the water out of the bottom. When it comes to soaking up water, bricks (and regular mortar) are far better than sponges.

Once you've been impressed with the roasting dish experiment, you may want to try it with your actual house wall. I wouldn't suggest you do this if you have a solid wall construction, but if you have a cavity wall, just setup a hose so that it is gently trickling onto the outside wall, just above the DPC for a few hours. Ideally on a dry calm day. If you don't beleive in rising damp, you'll be seriously impressed. As you observe the damp patch rising up your wall, imagine how much more effective it would be, if the entire bottom course of bricks were exposed to a constant source of water.

For all this, I still think that rising damp is very rare. A small crack in the DPC will only allow wicking at a very low rate, as this is rapidly dissipated through the rest of the wall and evaporation takes over, it's affects are kept very localised and generally quite minimal. I have yet to see an effective DPC spontaneously fail. IMHO it just doesn't happen. But then I have no experience of these new fangled injection systems. Perhaps they are prone to "fail", I just don't know.

 

[empip]

I recall when family built home in 50's, we placed all the bricks used in the old 40 gal'ish oil drums full of water ... hence they were all laid pretty well wet through (My job as a kiddie to replenish the soaked up waters by hosepipe) .. Allegedly to allow the mortar bedding to dry naturally without the moisture being drawn into the bricks.
BTW .. Residence remains standing unaffected by damp or subsidence.

Again a post of little overall consequence .. but factual.

Having said that ...... A venetian slant ..

Urban fragility
High water levels are also damaging the city's fragile architectural heritage. Materials such as wood and reed used to construct many historic buildings in the city are particularly vulnerable to water. And there is another problem as well. It is salt rise, or "risalita salina" as the Italians call it. Rising damp in brick masonry results in salt crystallization in the brick pores and damage to the bricks.

Tundo directs the Venice-based Interuniversity Consortium on Chemistry for the Environment.
The basements of many of the historic buildings in Venice are constructed from Istrian stone, a compact limestone with a very low porosity that is therefore impervious to seawater, Campostrini points out. "This special stone was imported from Istria in Croatia," he says. "As it was expensive and very heavy to be carried such a long way, it was only used for the basements in buildings."

Over recent decades, however, seawater has often risen above the basements and penetrated other types of materials used to construct buildings.
"Many efforts have been made to reduce the influence of rising damp, such as the use of mechanical or chemical damp-proofing, and a lot of experiments have also been carried out to remove salts from brick-wall masonry or marble structures," notes Vasco Fassina, director of scientific research in the Superintendency to Artistic & Historical Property of the Veneto Region and scientific consultant of the Veneto Institute for Cultural Heritage. Both organizations are based in Venice.

Fassina and coworkers have carried out a number of studies on water damage to historic buildings in Venice. They include a study of salt efflorescence on the marble slabs used to construct San Maria dei Miracoli Church between 1481 and 1488.

"The study showed that the concentration of the more soluble chlorides and nitrates increases with height because of rising damp, whereas the less soluble sulfates are concentrated and enriched in the lower part of the building," Fassina notes. Damp-proofing inserted "at the foot of the brickwork prevented further saltwater reaching the upper brickwork and stopped the increase in the concentration of soluble salts. However, these salts have continued their aggressive action on the marble. Desalination of the brickwork and stones is therefore necessary for conservation." Fassina's group has also investigated water infiltration in the crypt of St. Mark's Basilica in Venice and the brick decay resulting from salt crystallization. The crypt walls are below average sea level and are completely saturated with salt water.

More here -- A little on the heavyside, but someone is beavering away on the general problem :-
http://www.phys.tue.nl/nfcmr/cmrmain.html

 

[KonradFischer]

are impossible, because the capillary resistance between fine pored stone and rough pored mortar is extremly high, will say infinite. So the bigger pores of mortar can not suck up any water from fine pored stone. This is proven by a lot of examples and everybody can test it out at home:

You must only look to the next harbour wall, than you will see the next proof:

And look to old buildings standing totally in water:

Only the zone where the water flood and tide comes to is wet, above no rising damp at all. In a mortar layer the rising damp by capillary action comes in heavy conflict with gravitation, it can rise only few centimeters, not more. The reason of supposed rising damp normally is salt in the wall or/and water from leaky gutters or pipes, which comes in by natural sources form exterior. So only open your eyes, and all questions are solved.

The scientific background and further details - also what to do - you can find here:

Rising damp can not exist at all in masonry

 

[joe-90]

In the area where I live there is plenty of rising damp. All you have to do is look at garden walls etc and you will see the 'spalling' from frost damage and can see the hygroscopic salts in layers up the wall. Below the salt level the bricks are a darker colour than above.

It's just plain daft to say it doesn't exist just because you've never seen it.
I guess some bricks are more prone to it than others. These are Victorian bricks from a local quarry and are rather soft.

Have you ever seen a giant panda? Do they esist?



joe

 

[KonradFischer]

because I do not say there is no damp at foundation walls and garden walls and so on. What I say is that there is no capillary transport responsible for the damp. Its natural that rain is spraying on the walls nearby the ground, that salt can take up hygroscopic damp, but the salts will come in from exterior sources, not by capillary transports either.

Your giant panda joke I like very much. Works for God in heaven also, isn't it?

To learn more about rising damp take a look here:

Damp walls - what to do against?

Best regards

Konrad

 

[bathroomswap]

This has been an excellent thread. Very informative and, latterly, a good debate. Backs up a lot of what I've heard from a close friend who is a surveyor.

The RICS article was very good.

Konrad, you just hovered over this fiery debate and then emptied your watering can over it to end it in my opinion. Good site you have.

Glückliches Weihnachten !

 

[KonradFischer]

for your good wishes, which I will return with MERRY CHRISTMAS! And thanks for your friendly comment for my infosite. Atminstone similiar surprising may be this one: Thermal Insulation will cause Mould Attack and Loss of Energy. Another topic, but actual.

Best regards

Konrad

 

[oilman]

In the area where I live there is plenty of rising damp. All you have to do is look at garden walls etc and you will see the 'spalling' from frost damage and can see the hygroscopic salts in layers up the wall. Below the salt level the bricks are a darker colour than above.

It's just plain daft to say it doesn't exist just because you've never seen it.
I guess some bricks are more prone to it than others. These are Victorian bricks from a local quarry and are rather soft.

Have you ever seen a giant panda? Do they esist?



joe

A sadly typical joe post. Riddled with flaws. I have a garden wall spalled to hell, reason? water runs down it when it rains NOTHING to do with rising damp. I have a house wall 7metres high , some of the bricks are spalling, why? you guessed it, R A I N W A T E R. It is NOT rising damp. Now listen to Konrad, he seems to know quite a lot more than most of us. I take it the sun goes out at night, just because you haven't seen it.