Damp Internal stone with electro osmosis removed

[jimbo17263]

Hi , I'm currently renovating my property (1850's solid walls) and last year whilst removing my internal stone pointing I removed an electro osmosis system. Now the stones that had the anodes installed have become damp. never noticed a problem before.

Also as BC is involved I have and to use a twin layer of visqueen, either side of insulation before concreting the floor, just wondering if this is now pushing moisture to the walls?

just wondered if anyone has any advise on how best to remove the damp?

Should I hire an industrial dehumidifier to remove the damp then install a new osmosis system. or use a different method like chemical injection.

Also as I'm re-pointing the stone feature walls, I've read that I lime mortar should be used to help the stone breath, is this true or could I just use normal mortar.

Cheers in advance for any advice

 

[theprinceofdarkness]

Looks as though the electro osmosis system was working, why did you remove it? I used lime mortar for a rock feature wall but because it looks nicer, get some really white sand for it. If you use cement and some grotty old red sand it will look gloomy. As for the damp, I have a limestone cottage and have had no problem with the DPCed floor "pushing" the damp into the walls. The real secret is to lower the water level around the building by the means of french drains/tanking etc. Imagine that you have a tiny little stream flowing , say 6" under your floor, so the earth is damp and the flag flooring is damp but the water is evaporating away so it never really appears. If you now cap the floor with a DPC, it can't evaporate away other then through the walls, the water level rises and is evident by dampness in the walls.
Exactly what is the construction of your house, many described as "solid walls " are actually rock and rubble, two skins of finished blocks with a load of rubbish used as the infill. Also the stone type, mine is limestone which is pretty impervious, other types , such as sandstone are like a sponge.
Frank

 

[jimbo17263]

Hi Frank, not sure why I remove it. Read a lot of info about does it/doesn't work, and it now seems that it does work, d'oh. cheers for the info about the mortar. Unable to use a French drain type system as I'm in the centre of town and my front step is the road, at the back its a shared yard, with gas + water & drains running beneath. The main area of visual damp is from the party walls, the walls are a Yorkshire stone and with what I can see, I think rubble filled. all sat on a clay bed. took some pics this morning to show you what's happening.

 

[vinn]

Electro-Osmosis DPC systems are by and large a rip off - serendipity of other coincidental factors might give the impression that it works.
In your case: removing the previous plaster or render, and installing a membrane might have created or exposed damp conditions.
It could also be that you didn't actually notice the damp before.
Where is the damp on your photos?

Presumably, the external wall surface is rendered? What condition is it in?
Is the FFL higher than the outside ground level?
Rendering the internal surfaces with a sand and lime mix at 4:1 will work for a number of years in your walls.
Keep the render 50mm above the FFL.

FWIW: why does photo 2 show a step down?