Abstract: An expansion ring assembly and method for sealingly installing a gasket within an opening in a wall of a structure. The expansion ring assembly includes an expansion ring having first and second adjacent end portions, and first and second cam members are rotatably coupled to the first and second end portions. Each cam member includes tool engagement structure for rotating the cam members, and cam surfaces of the cam members are engageable with one another such that, upon rotation of each cam member, the cam surface thereof engages the cam surface of the other cam member to drive the first and second end portions of the ring apart from one another, thereby radially expanding the ring to compress a gasket into sealing engagement with the wall opening. Only one cam member may be rotated, or alternatively, both cam members may be rotated sequentially, depending upon the amount of expansion which is needed.