a cornice molding cap is provided as an accessory to cover or eliminate gaps created where cornice molding meets at a corner of a building . the cap covers gaps where cornice molding meets at a corner structure formed by two walls . the cap is particularly useful in exterior siding installations at corners not employing corner posts having receiver pockets for cladding material end edges . a method of finishing a corner molding installation is described , as is a system for finishing such installation , and an assembly including a unitary cornice molding corner cap .