Hello, I live in a 300 year old stone built house, halfway up a mountain in west Wales. Have about 90" rain a year driving from the west - much of it horizontal, house has been dry until I had a lean-to steel frame conservatory installed recently by a well regarded local company who have done other fine work for me. Water now dripping forcefully down the house wall inside conservatory but only from along the line of its apex & also leaking to the inside of the house at the same point above the door lintels. Lead flashing seems fine, sunk into stone & mortar by 2", the sealants also fine. Have re-pointed entire wall, same problem. Company says porous rock to blame. If this is so why dripping only at this horizontal level? Any ideas of where to go with this next & if I need professional help do I call a local builder, surveyor, architect? Thank you for any replies.