P
Phil189345985
Exploits some useful features of physics, thanks, called fluid dynamics. Google it (sorry, I don't have to tell you to do that , do I?).Don't kid yourself mate. You can't alter physics.
RISING DAMP
- Thread starter sophski
- Start date
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Just a comment on all this rising damp nonsense and then I’ll try to give Sophie some advice.
Rising damp is very easily replicated in a workshop – I’ve seen it - so it's plain wrong to say it doesn't exist. So why do some say it doesn't exist? I'll tell you.
Thirty or forty years ago we dramatically changed the way we treat and live in old houses. Basically we introduced much higher levels of insulation but at the same time we sealed them up. Not just in terms of ventilation; we also fitted impermeable floor coverings and paints and replaced breathable lime mortars with dense impermeable cement, plus a whole load of other things that altered the way a building works. One of the main consequences of all this was a massive increase in condensation dampness. So where a bit of condensation dampness would have gone unnoticed or would have quickly evaporated off, what now happens is it gets trapped in the fabric of the building. It builds and builds until it reaches saturation point and then it starts to spoil the decorations. We understand this now but it was much less understood 20-30 years ago. Back then people saw dampness at the base of a wall and automatically diagnosed rising damp. And, I suppose, some still do.
About the same time so called damp proofing technology also changed. It got much easier. You didn’t need much by way of skill. Hack off plaster, inject, re-plaster. Six grand please? It was very easy money. And where there’s easy money you’ll get plenty of people ready to cash in. The industry went through the roof – mostly filled with scammers who knew little or nothing about what they were doing. But then came the backlash. A bloke called Jeff Howell went around properly testing these works. He didn’t find any rising damp. Not surprising since most of it was condensation! He wrote a book about it called the Rising Damp Myth. It came at exactly the right time. By then the damp proofers had a terrible reputation for poor workmanship and disappearing off the face of the Earth when the dampness came back. A lot of people had burned a lot of money and they still had damp walls.
The book became VERY popular with university lecturers. It was the latest NEW thinking. I can tell you from direct experience it was very trendy to promote the rising damp myth and if you dared to be different you were labelled as being a bit of a dinosaur. The odd thing at the time was that while all this new thinking was being written up in essay after essay, there were brick and block wall experiments in the materials tech lab which clearly had rising damp up to about 150mm. (that’s small sections of walls built in water trays)
Soooo, rising damp does exist, no question. But it is not that common and often (usually) confused with other sources of dampness.
Rising damp is very easily replicated in a workshop – I’ve seen it - so it's plain wrong to say it doesn't exist. So why do some say it doesn't exist? I'll tell you.
Thirty or forty years ago we dramatically changed the way we treat and live in old houses. Basically we introduced much higher levels of insulation but at the same time we sealed them up. Not just in terms of ventilation; we also fitted impermeable floor coverings and paints and replaced breathable lime mortars with dense impermeable cement, plus a whole load of other things that altered the way a building works. One of the main consequences of all this was a massive increase in condensation dampness. So where a bit of condensation dampness would have gone unnoticed or would have quickly evaporated off, what now happens is it gets trapped in the fabric of the building. It builds and builds until it reaches saturation point and then it starts to spoil the decorations. We understand this now but it was much less understood 20-30 years ago. Back then people saw dampness at the base of a wall and automatically diagnosed rising damp. And, I suppose, some still do.
About the same time so called damp proofing technology also changed. It got much easier. You didn’t need much by way of skill. Hack off plaster, inject, re-plaster. Six grand please? It was very easy money. And where there’s easy money you’ll get plenty of people ready to cash in. The industry went through the roof – mostly filled with scammers who knew little or nothing about what they were doing. But then came the backlash. A bloke called Jeff Howell went around properly testing these works. He didn’t find any rising damp. Not surprising since most of it was condensation! He wrote a book about it called the Rising Damp Myth. It came at exactly the right time. By then the damp proofers had a terrible reputation for poor workmanship and disappearing off the face of the Earth when the dampness came back. A lot of people had burned a lot of money and they still had damp walls.
The book became VERY popular with university lecturers. It was the latest NEW thinking. I can tell you from direct experience it was very trendy to promote the rising damp myth and if you dared to be different you were labelled as being a bit of a dinosaur. The odd thing at the time was that while all this new thinking was being written up in essay after essay, there were brick and block wall experiments in the materials tech lab which clearly had rising damp up to about 150mm. (that’s small sections of walls built in water trays)
Soooo, rising damp does exist, no question. But it is not that common and often (usually) confused with other sources of dampness.
Sophie, it is difficult to work all this out without seeing it first hand, so I'm afraid some of this is going to be general information. I think you are saying that the dampness has got worse as time has gone on. That would indicate it is more likely to be related to how you use the house rather than an increasing source. You also mentioned part of the dampness may have got worse after laying the laminate floor. It is possible that your floor has always been a bit damp but not so much to cause an obvious problem. You then cover the floor with laminate and this pushes moisture (or moisture vapour) to the edges. One way to check this is lift a section of laminate and see if there is dampness underneath. Then re-lay the laminate temporarily on a sheet of polythene. Leave it for a month or two and lift it again. Is there moisture under the polythene or on top?
Check outside when it’s raining. (as somebody else suggested) Make sure the gutters and drains are not backing up or overflowing. Also check your hard surfaces and make sure they are not pooling up against the house. If you’ve got any of this you need to get it sorted.
The damp walls are not likely to be rising damp but there are tests that can be done that will prove it one way or the other. If you really want to be certain get a specialist in to carry out some tests for you. Not a treatment company. Go to a chartered surveyor that specialises or an independent damp specialist. It will cost you but at least you’ll then know for sure.
That said it is more likely to be interstitial condensation. This is water vapour that condenses within the wall and manifests as dampness on the surface. The reason it occurs at the base of the walls is because that’s where the walls are coldest – due to cold bridging with the sub-floor. There are two basic options really; you can tackle the wall itself (with insulation or a thermal break) or you can alter the environment. The first option is disruptive so if you are not going to be knocking stuff about anyway you will probably want to try altering the environment first. Basically that means reduce moisture sources, keep a bit warmer and increase ventilation.
Check outside when it’s raining. (as somebody else suggested) Make sure the gutters and drains are not backing up or overflowing. Also check your hard surfaces and make sure they are not pooling up against the house. If you’ve got any of this you need to get it sorted.
The damp walls are not likely to be rising damp but there are tests that can be done that will prove it one way or the other. If you really want to be certain get a specialist in to carry out some tests for you. Not a treatment company. Go to a chartered surveyor that specialises or an independent damp specialist. It will cost you but at least you’ll then know for sure.
That said it is more likely to be interstitial condensation. This is water vapour that condenses within the wall and manifests as dampness on the surface. The reason it occurs at the base of the walls is because that’s where the walls are coldest – due to cold bridging with the sub-floor. There are two basic options really; you can tackle the wall itself (with insulation or a thermal break) or you can alter the environment. The first option is disruptive so if you are not going to be knocking stuff about anyway you will probably want to try altering the environment first. Basically that means reduce moisture sources, keep a bit warmer and increase ventilation.
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Thank you for your information and advice John. But I have a question mark over the chimney, as I have now seen a few damp patches on the top of the wall where the old fire backs onto. Shat are your thought and experience of this coursing the damp? Thanks
Old chimneys often cause dampness issues. If you look down the flue when a fire is going, at certain times it can literally be running with water. Over the years that water soaks into the masonry and mortar joints and contaminates the wall and plaster. That contamination causes dampness and staining on the internal plaster surface. First thing I would do is make sure it is actually dampness. What looks like dampness might just be staining. It can be hard to tell them apart.
Chimneys are also a weak spot in the construction. Older ones often had no damp proof course built in, so if the masonry gets saturated with rainwater it will eventually seep into the walls below. Water might also get in around the pot, through the mortar weathering on top (called the flaunching) or into the masonry itself via poor joints or rendering. If the lead flashings are not properly fixed water will obviously get in there as well. So if it does turn out to be dampness these things need to be checked.
Also make sure the chimney is well ventilated. (I can't remember if you said the chimney is used or not)
Chimneys are also a weak spot in the construction. Older ones often had no damp proof course built in, so if the masonry gets saturated with rainwater it will eventually seep into the walls below. Water might also get in around the pot, through the mortar weathering on top (called the flaunching) or into the masonry itself via poor joints or rendering. If the lead flashings are not properly fixed water will obviously get in there as well. So if it does turn out to be dampness these things need to be checked.
Also make sure the chimney is well ventilated. (I can't remember if you said the chimney is used or not)
Your eyes must have been running with water as well jeds.
No we don't use it, we moved in last November and dint see an issue then. Unsure if it was used by previous owners. May be why I'm seeing damp now it's not being used?. From your experience how would you go about solving the problem if it is the chimney causing this? I am in the process of getting a professional to come and hopefully find the cause.
Best get a cowboy in then - just to be on the safe side.
well looks like no one agrees on this site, tbh all this has just really given me a head ache and not much else. So i guess im on my own again.Check the ventilation to be begin with. Maybe do a smoke test to make sure it's drawing. You can buy a box of test matches or pellets from a local DIY. Secondly make sure it is definitely dampness and not staining. If dampness, is it penetrating dampness or condensation dampness? Either way you will have to track down the source. Staining is usually slightly brown in colour rather than just dark and it's more likely to correspond with the centre of the flue. (which might not be the centre of the breast) If it's staining you could try a stain block but that is usually only good for a short term. The only certain remedy is hack off and re-plaster. Unfortunately old chimneys are always a bit of a pain, especially when they are not used. There's lots of possible problems and sometimes it could be a combination of two or more.
PS. beware of trolls. If you work through it logically all things can be solved.
How do you mean check the ventilation?(sorry first house and clueless).the dampness feels wet to touch and is yellow in colour with paint peeling. This pic is of the wall in the living room shared with the chimney breast in kitchen.
(top of wall)
(bottom)
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