Electro Osmosis - DPC's
- Thread starter bogblock
- Start date
It all depends on the whys wheres, whos, and whats of your situation.
I seen hundreds of installations.
Some have worked others have not, but I think in all honesty if you really have a rising damp problem there are better methods out there these days.
Do a search on this forum and you will find plenty of advice on rising damp, some good, some not so good.
I seen hundreds of installations.
Some have worked others have not, but I think in all honesty if you really have a rising damp problem there are better methods out there these days.
Do a search on this forum and you will find plenty of advice on rising damp, some good, some not so good.
I'm amazed that anyone still takes these hocus pocus electro osmotic systems seriously.
This is what the Building Research Establishment has to say about electro-osmotic DPCs:
"There are two types: active and passive; neither has been approved by a recognised laboratory. By far the greater number of systems are of the passive kind, where there is no external source of electricity. They have always been something of a controversial issue. On theoretical grounds, it remains a mystery as to how they can work; their effectiveness has not been demonstrated in the laboratory and field evidence is disappointing.
Active electro-osmotic systems use an external source of electricity. BRE has no evidence to suggest that the two types behave differently in practice, though some of the active systems may be rather susceptible to the effects of mechanical damage and electrochemical corrosion...
...The claim for passive types is that a damp wall contains an electrical potential and the earthing of this potential causes the dampness to fall. It is true that the existence of electrical potentials in a damp wall can be demonstrated. However, where such potentials are caused by the movement of moisture and salts in the first place, earthing the potentials might be expected to increase rather than reduce the upward flow of moisture and salts.
The installations inspected by BRE were coupled with a replastering system which provided a good barrier to moisture; it is suspected that claimed successes for the system relied heavily on the render and plaster system. As far as is known the passive system is no longer available, though many thousands of installations still exist. Active systems do attempt to make use of true electro-osmosis: the movement of moisture through finely pored materials under the influence of an electrical field. Site experience is not encouraging and, again, the systems rely on the assistance of plaster to contain moisture.
Of the complaints about electro-osmotic damp-proofing that BRE has investigated, some have involved condensation problems that the installation could not be expected to cure; in others there appeared to be at least partial failure of the system, suggesting that electro-osmotic systems are not effective in preventing rising damp in walls in all conditions."
Source - BRE Understanding Dampness - see http://www.brebookshop.com/details.jsp?id=145268
This is what the Building Research Establishment has to say about electro-osmotic DPCs:
"There are two types: active and passive; neither has been approved by a recognised laboratory. By far the greater number of systems are of the passive kind, where there is no external source of electricity. They have always been something of a controversial issue. On theoretical grounds, it remains a mystery as to how they can work; their effectiveness has not been demonstrated in the laboratory and field evidence is disappointing.
Active electro-osmotic systems use an external source of electricity. BRE has no evidence to suggest that the two types behave differently in practice, though some of the active systems may be rather susceptible to the effects of mechanical damage and electrochemical corrosion...
...The claim for passive types is that a damp wall contains an electrical potential and the earthing of this potential causes the dampness to fall. It is true that the existence of electrical potentials in a damp wall can be demonstrated. However, where such potentials are caused by the movement of moisture and salts in the first place, earthing the potentials might be expected to increase rather than reduce the upward flow of moisture and salts.
The installations inspected by BRE were coupled with a replastering system which provided a good barrier to moisture; it is suspected that claimed successes for the system relied heavily on the render and plaster system. As far as is known the passive system is no longer available, though many thousands of installations still exist. Active systems do attempt to make use of true electro-osmosis: the movement of moisture through finely pored materials under the influence of an electrical field. Site experience is not encouraging and, again, the systems rely on the assistance of plaster to contain moisture.
Of the complaints about electro-osmotic damp-proofing that BRE has investigated, some have involved condensation problems that the installation could not be expected to cure; in others there appeared to be at least partial failure of the system, suggesting that electro-osmotic systems are not effective in preventing rising damp in walls in all conditions."
Source - BRE Understanding Dampness - see http://www.brebookshop.com/details.jsp?id=145268
Yawnnnn.
What do you think I was saying.
Unfortunately unlike you and a few more on this forum, I cannot diagnose the cause of a damp problem on the basis of a few remarks made by some householder.
You and your ilk are no better than the cowboys who sell a dpc to somebody when the cause of the damp is not rising damp.
By your comments you have probably managed to dissuade a few gullible people, that there is no such thing as rising damp, and that replastering will cure the problem.
A dpc does not just prevent a wall from getting wet, it serves other purposes.
Have you ever seen an outbreak of dry rot that has started in the ground floor timbers and continued up to the first and second floors, all because the dpc had failed.
Probably not or you would not continue to show your ignorance on this subject.
Thanks for the BRE link Fred62. At £42 a copy it's worth a visit to the library.
Please bear in mind that my original post asked for any experience of electro osmosis. I know of only one local installation, which apparently worked, given a few months to take effect.
Anobium's comment about the circumstances is a fair one, so I'll elaborate if anyone is interested. I searched the forum before my first post, hence the comment about the number of opinions.
I'm afraid it does go on a bit.
I live in a rendered bungalow in Devon. There is a garage built of solid block attached to the end wall. The garage has a DPC in the walls and was probably built in the 60's. I am converting it into a kitchen and building a utility room outside it, so what is now the outside wall of the garage will become an internal wall.
The garage floor is solid and I've dug a bit out against the original end wall of the house. There is no membrane beneath the four inches or so of concrete in the floor and no sign of a DPC in the original end wall of the bungalow, which is in brick.
Heating is by conventional radiators. All the floors in the living accomodation are suspended timber. All the windows in the bungalow are single glazed and suffer from condensation. There is no forced ventilation in either the bathroom or the kitchen. I am treating the symptom at the moment by leaving some windows ajar and using a dehumidifier. We do see the odd patch of mould on the inside of the end wall, usually behind furniture.
Having browsed the forum, all this seems to me to suggest that there is, at least, a ventilation problem. I intend to deal with this by fitting trickle vents to the existing window frames, and fans in the new kitchen and the bathroom.
Given that I may have to dig out the existing garage floor and expose the original end wall below floor level, it would seem to me to be the ideal time to install a DPC. Even if it isn't necessary, I think it would be a wise precaution before the kitchen is fitted.
If you've got this far, thanks for your forbearance!
Any opinions?
Cheers
Bogblock
Please bear in mind that my original post asked for any experience of electro osmosis. I know of only one local installation, which apparently worked, given a few months to take effect.
Anobium's comment about the circumstances is a fair one, so I'll elaborate if anyone is interested. I searched the forum before my first post, hence the comment about the number of opinions.
I'm afraid it does go on a bit.
I live in a rendered bungalow in Devon. There is a garage built of solid block attached to the end wall. The garage has a DPC in the walls and was probably built in the 60's. I am converting it into a kitchen and building a utility room outside it, so what is now the outside wall of the garage will become an internal wall.
The garage floor is solid and I've dug a bit out against the original end wall of the house. There is no membrane beneath the four inches or so of concrete in the floor and no sign of a DPC in the original end wall of the bungalow, which is in brick.
Heating is by conventional radiators. All the floors in the living accomodation are suspended timber. All the windows in the bungalow are single glazed and suffer from condensation. There is no forced ventilation in either the bathroom or the kitchen. I am treating the symptom at the moment by leaving some windows ajar and using a dehumidifier. We do see the odd patch of mould on the inside of the end wall, usually behind furniture.
Having browsed the forum, all this seems to me to suggest that there is, at least, a ventilation problem. I intend to deal with this by fitting trickle vents to the existing window frames, and fans in the new kitchen and the bathroom.
Given that I may have to dig out the existing garage floor and expose the original end wall below floor level, it would seem to me to be the ideal time to install a DPC. Even if it isn't necessary, I think it would be a wise precaution before the kitchen is fitted.
If you've got this far, thanks for your forbearance!
Any opinions?
Cheers
Bogblock
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