looking for a way to fill the 3" gap between brick wall and plywood ceiling above. it is indoors (it is an addition to the house if you are wondering).
i'd like to seal the gap to eliminate egression point for insects and air exchange with the attic. I've thought of putting a piece of plywood then sealing it w/ tape and mud. but i think the mud might be sloppy on the brick.
after sealing it, i'll put a crown moulding to cover this.