Part of our house is 200 years old and the walls are cob. A bathroom has been started upstairs, but was never completed 25 years ago due to concerns about the sewage pipe having to go through the very thick and crumbly wall. We think this can be done these days using some kind of sewage processing unit. I was wondering if anyone has this kind of house situation, any advice, or recommendations for builders in Cornwall to do this kind of work. The wall has an old doorway below and a window above so it might be a bit fragile. Also am worried that so many houses I've cleaned in have had leaking showers upstairs at some point and water pouring through the ceiling- that would be very bad news!...