MULLION JOINERY FOR WINDOW FRAME ASSEMBLY

The disclosure relates generally to a window assembly designed to facilitate the construction process by providing a simple and efficient method for joining mullion members and frame members along a window joint. The assembly includes a mullion end cap with a seal extending around the periphery of the end cap to help minimize moisture entry into the window assembly via the window joints. In addition, the seal includes fastener bosses designed to seal against fasteners extending therethrough to help seal the joint without need for separately applying a silicone or other sealant in a post-assembly process.