An assembly for sealing a space between a secondary structure movable into and out of a primary structure includes a base member mountable to an outer surface of the secondary structure and a flange member. The flange member includes a main flange portion and a coupling portion extending from the main flange portion. The main flange portion includes a first portion and a second portion. The second portion is on the opposite side of the coupling portion from the first portion. The coupling portion is couplable to the base member such that the first portion is adjacent a rear wall of the secondary structure and the second portion extends beyond the outer surface of the secondary structure when the coupling portion is coupled to the base member. The second portion is configured to engage an interior surface of the primary structure when the secondary structure is in the extended position.