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Rising damp is a myth!

8th August 2009

Every so often the surveying profession is hit with ‘there’s no such thing as Rising Damp’ headlines. It happened again last month, with the Architects Journal proclaiming ‘Rising Damp is a Myth – so says former RICS chief’. The quote was attributed to Stephen Boniface a past chairman of the Building Surveying Faculty of the RICS and someone whose opinions I have time for. It was endorsed by Elaine Blackett-Ord the chair of the Register of Architects Accredited in Building Conservation who went further and said that rising damp is ‘rarer than rocking horse **** (waste products)’.

Needless to say this provoked an outcry, similar to the outcry last time it was proclaimed back in 1998 and before that in 1995. After all there is a significant industry set up to eradicate rising damp from our homes, so if a learned and experienced group of professionals say that there isn’t such a thing as rising damp, then it could seriously threaten their livelihoods.

The major stumbling block to all of this is there has never been an in depth study into rising damp. Yes that surprised me as well.  There have been studies which show that some retro fit damp proof courses don’t work but not that the dampness was only caused by ground moisture soaking into and rising up into the wall.

Laboratory tests have been carried out where a pier of bricks were constructed and set into a tank of water. The pier was monitored over a period of time and, depending upon which study you read, the pier either showed dampness up to 500mm (20”) high or no damp at all. It seems to depend upon the brick type, the mortar type and who did the test.

So if I inspect a property and find the wall is damp some 900mm (3’0”) above ground level, it now seems I must presume that it has a cause that isn’t rising damp. For example it’s damp seeping through the wall from leaking pipes or gutters or its from condensation caused by the occupants of the house. Sorry, but if I find damp at skirting level on an inside wall then its unlikely to be from either of those sources.

Similarly I have been involved in countless properties where a retro fit damp proof course has been installed. I also know of homes where there was dampness before and a damp proofing system has now been installed and there is dampness no more. So if the dampness before wasn’t rising from the ground but it was from some other cause, then at least the damp proofing system has solved it.

You will note I refer to a damp proofing SYSTEM and not a damp proof course. That’s because an integral part of the treatment is to remove the damp affected plaster and replace it with a new plaster that can resist any dampness and salts that may have been left behind by the rising damp before the injected barrier was installed.

It was claimed some years ago that retro fit damp proof courses only worked because of the other works of renovation going on at the same time, such as installing central heating, re-pointing the walls and replacing the gutters. There is no doubt that these extra bits will help to keep the building dry but nowadays the retro damp proof courses are often fitted in isolation of complete renovation and they are still successful.

So what can we take from this. Yes there are instances where damp proof courses are installed when the problem isn’t rising damp. I haven’t seen an example where installing a damp proof system has exacerbated the dampness problem. Maybe there are instances where better ventilation of the lower wall and even land drainage adjacent to the building will remove the problem. But I don’t think that rising damp is a myth, its just not as common as people think.

 


One Response to 'Rising damp is a myth!'

  • Riccardo

    Similarly, I had damp at skirting level in my kitchen. The walls did have damp proof courses, but they were bridged internally by rubble. I took four bricks out, removed the rubble and replaced the bricks.

    It could have been penetrating damp, but that requires rain, and it was quite dry weather in the weeks leading up to my getting around to carrying out the work.

    Since rising damp is a myth, it wasn’t rising damp, so this shouldn’t have cured it, but now the wall is no longer damp. What a marvellous co-incidence!

    Thursday, September 1st

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