Please can you advise me . I have a corridor and a room along side an exterior wall that has dropped sometime in the past . As a result of this both the corridor (which is approx 1 metre wide, 3mitres long) and the room (4metres long x 4 metres wide) fall away along the wall by up to 22,5 mm from level . The floors are made of brick laid on edge on top of concrete , they are dry ,clean and stable , but have slight variations on hight between the bricks and the mortar . I want to lay other flooring on top of this rather then have to take up all the bricks and lay a screed . I will use a wide engineered floor board (18mm thick) in the hall , and rubber floor in the other room . Can a levelling compound deal with a difference of 22.5 mm in the level over a 1 metre wide corridor ? If so which type ? Steve