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Hi,
I am renovating an old house in France, which has stone walls. They are really thick at the base (1m or more), made from random chunks of local stone (granite sort of stuff) with mud mortar (yes - mud!). One wall in particular is giving me grief. Before we started in this room, it had a dirt floor. During the early stages of renovation we had to rip out the old soil pipe, which ran under this floor, at a shallow depth. I got a call from the builder a few days later to tell me that after a period of rain, the trench left where the pipe had been, near the front wall, had filled with water. He dug a drain outside the front wall, and after a few days the water had gone. (We now have two 'french drains' running down the front an rear walls of the property). A while later, the builder removed the top few inches of all the dirt floor, laid a modern damp proof membrane, and put down a concrete floor. At the same time the outside of the house was completely rendered in a traditional lime render, and painted with masonry paint. The project then stalled for a long time...
When I returned to France to see how things were, I noticed that the long side wall (which had always been fine) was now very damp to a height of 1m or more. There were lots of efflorescent salts to be seen too. The wall contains a large open chimney, and I wondered if rain coming down there could be responsible, but it along the whole wall. It would seem that a combination of the new floor, and the exterior render are the cause. If the water table is as high as it seems to be (the experience of the self-filling trench), then I guess the damp proof membrane will be pushing all the water out sideways - where it will meet the mud-mortar wall, and it looks like this is acting like a sponge. The old dirt floor probably let it all evaporate away...
My question is this - what is the best approach to solving this? I want a 3rd french drain putting in - down the side of this wall, to see if this lets the water run away. If this fails, would an injected DPC work on this sort of wall? Or maybe an osmosis system? All help gratefully received.
There are odd spots of damp in other parts of the house too. Worst one is on the party wall, where there's no chance of digging an external drain. I guess that's going to have to be injected, or painted over with some sort of barrier paint....
Cheers,
Doug
I am renovating an old house in France, which has stone walls. They are really thick at the base (1m or more), made from random chunks of local stone (granite sort of stuff) with mud mortar (yes - mud!). One wall in particular is giving me grief. Before we started in this room, it had a dirt floor. During the early stages of renovation we had to rip out the old soil pipe, which ran under this floor, at a shallow depth. I got a call from the builder a few days later to tell me that after a period of rain, the trench left where the pipe had been, near the front wall, had filled with water. He dug a drain outside the front wall, and after a few days the water had gone. (We now have two 'french drains' running down the front an rear walls of the property). A while later, the builder removed the top few inches of all the dirt floor, laid a modern damp proof membrane, and put down a concrete floor. At the same time the outside of the house was completely rendered in a traditional lime render, and painted with masonry paint. The project then stalled for a long time...
When I returned to France to see how things were, I noticed that the long side wall (which had always been fine) was now very damp to a height of 1m or more. There were lots of efflorescent salts to be seen too. The wall contains a large open chimney, and I wondered if rain coming down there could be responsible, but it along the whole wall. It would seem that a combination of the new floor, and the exterior render are the cause. If the water table is as high as it seems to be (the experience of the self-filling trench), then I guess the damp proof membrane will be pushing all the water out sideways - where it will meet the mud-mortar wall, and it looks like this is acting like a sponge. The old dirt floor probably let it all evaporate away...
My question is this - what is the best approach to solving this? I want a 3rd french drain putting in - down the side of this wall, to see if this lets the water run away. If this fails, would an injected DPC work on this sort of wall? Or maybe an osmosis system? All help gratefully received.
There are odd spots of damp in other parts of the house too. Worst one is on the party wall, where there's no chance of digging an external drain. I guess that's going to have to be injected, or painted over with some sort of barrier paint....
Cheers,
Doug