Not been on here for a while...hoping for some ideas on a little project I'm involved in...

One bedroom, double fronted, terrace cottage of solid brick walled construction, except the back wall which is stone and is earth sheltered up to about 1.5m above internal ground level with a tarmac lane running directly along it (so no land at the back). Quarry tiled floors internally, not in bad shape with a bit of TLC.

There is definitely water getting in through the back wall. You can actually see the patches of damp plaster forming when it rains heavily. The guttering is leaking at the back so that isn't helping and there are some pointing repairs at the junction between the road and the wall to attend to. I've had the damp proofing guys in and they say strip all the plaster off, dig the floors up and tank everything with K11, new concrete floor etc, or a membrane with a drain.

I'm just wondering if there is some way of dealing with the problem by working with the building somehow, e.g. expose the stone wall and leave the quarry tiles down as a finished floor surface and let the moisture evaporate into the room and be dealt with through ventilation? The heat source will be a wood burning stove, passive stock ventilation and the client wants sash windows so there is going to be plenty of air flow to dissipate moisture. The roof and the other external walls are all being insulated internally. All the windows are on the south facing side and the house is only 3.5m deep and I'm thinking the solid floor and mass of the back wall could be a useful thermal buffer to moderate the internal temperature...

Any thoughts? The cottage doesn't smell damp particularly although there is evidence of rot in the skirting boards.

What Tony said. Fix guttering and pointing and see what difference it makes. If you still get damp problems on the wall more drastic action probably required. I wouldn't rule out tanking membranes down to a drain if the water is getting in that quick you can see it. What level of ventilation does it have at the moment?

Has the level of the lane been raised over the years so the level has gone above any tanking? If that's happend the highway authority might well be liable to fix the problem.

I think you also need a chat with the client. Is he the type that's going to complain the quarry tiles are cold in the winter. Does he understand that there is a different risk with each of the proposed damp solutions and that not all have a warranty? Is he going to be calling up to complain at the first hint of damp? If you decide later that it hasn't worked and has to be tanked and a drain installed, that would be pretty disruptive if by then they are living in the place and have carpets and skirting etc. Basically means turning it back to a building site.

If house only 3.5 m deem then does the rear wall make up a significant percentage of the wall area? Could be pretty cold if that wall isn't insulated. Are they are likely to try reducing ventilation to make to warmer?