So, this kitchen of mine has been rather problematic. Information on Kitchen and house: built ~ 1900 terraced, kitchen extension installed ~ 1970, approximately 6m x 4m, 3 external and 1 internal walls, walls are ~1.5ft thick, solid concrete floor, 1 large window double glazed, 1 chimney breast and 2 alcoves all sealed up with bricks, outside walls are north south east, east wall is back onto a raised garden. ~1ft gap between garden and house but top is covered. whole kitchen is ~1ft above outside ground level bar the east wall. To begin with we ripped out the old 70's kitchen and when we did behind most of the cupboards was black mould. So we cleaned the mould away and let it dry thoroughly. Our initial thoughts was rising damp, but we dismissed this as there was no damage to any of the walls and no signs of cracks or tide marks. The only thing we could see was water marks where it seems water was running down the wall but not from any cracks or the ceiling. We had a company come in and the guy prodded his little tool in the wall took some readings, went outside and made some observations. He wanted to tank all the walls. We took his advice and moved on. Needless to say the price was astronomical. In the £4500 region. So we sought another opinion. We got another company in and they said that it was not rising or penetrating damp. They suggested thoroughly cleaning the walls and leaving to dry then applying a membrane to the wall, the plastic membrane, and then plaster boarding over the top. This was done. New kitchen installed. After 4 months, everything was good. No mould and no damp at all. I removed plinth and checked underneath. 3 months later I noticed at the back of the house that there was a crack in the cladding caused by the stone garden wall collapsing and putting strain where it joined against the outside of the house. I removed the excess and repaired the hole. At the same time I noticed that there was a hole left in the wall going to the back of the units from where the original waste pipe was removed for the sink. I filled this as well. Now under a month later and there is black mould behind the units going up about 0.5ft. This is behind all the ground cupboards except the fan oven and its housing. Im guessing the ovens fans are producing ventilation as this wall was moulded previous to installation. Needless to say I have re opened the hole. I am wandering if this is indeed my theory that it is all caused by condensation or if it is rising damp. Also note there are signs of water running down the walls. Dehumidifier was reading ~80% humidity. Keeping it at about 50% now. Any advice would be great.