Hi, My husband and I are (very very slowly) renovating an old farmhouse in France. The house is on a flat bit cut in to quite a steep slope. We find that the inside of the walls at the back of the house are quite damp. So we want to put a drain along the back of the house. We know nothing, but after extensive reading of the internet we think a fin drain sounds what we want. A french drain could work perhaps, but the problem is made worse by a soak away pipe which runs along the back of the house (we want to replace with solid pipe until past the house then have the perforated pipe, but it means there is not much room for the drain and fin drains look to be very narrow.
However we are struggling to work out EXACTLY what we need to do. On the page on the website http://www.pavingexpert.com/drain07.htm it shows you can wrap the pipe in the membrane, or that the membrane can go in to the pipe. Looking at suppliers sites we see the first option is almost exclusively used - we thought maybe because a slit all along the pipe to let the membrane in would also let soil in?
In the case where the perforated pipe is wrapped in the membrane we don't understand why the water goes in to the pipe and not in to the surrounding soil. Can anyone explain?
Should the membrane be right up against the wall?
Thanks for any help
It isn't like there is a stream behind the house, but when it rains the ground there is generally wettish rather than awash, then we notice in the garage (which is beside the house) that damp slowly spreads across the floor.
The ground is quite sandy so rain that has fallen uphill of the house soaks in quickly and doesn't flow past the house but we guess ends up against the wall and eventually soaks through.
The house doesn't have a basement and none of it is under ground apart from the foundations. It is an old stone building so not sure how much foundation there is. I don't know how thick the soil is but I don't think the house is standing on rock. Not sure if that helps
