Chris Plastow
Ok. Clearly this has nothing to do with membranes ! The drain leak you experienced previously was I assume outside the building? The crack or area where the water entered from this will continue to leak from rain water, it is a weakness in the structure and must be located and addressed or dampness will continue, internal wall tanking will not solve this, it will just direct the water to the floor, which is where I think you are now. Is the floor currently covered with anything like carpet or laminate?
