I have recently moved into a house where patio doors have been fitted after removing a window and wall . In place to cover the cavity gap was a wooden threshold board which was not seated properly . So i have removed this to find the only support on the outer wall was a poorly fixed batten to support the board.
Can i use DPM to cover the cavity and fill with cement and then my flooring can reach completely to the door frame OR replace the threshold board but how do i score to the outer wall to support ?