Abstract: A closure assembly includes a frame having at least one hollow end rail and a pair of side rails coupled in butt joints to opposed ends of the end rail. The butt joints include a core extending through the hollow end rail and from opposed ends of the end rail through openings in the side rails into the interiors of the side rails. A saddle within each side rail interior straddles a corresponding end of the core. A fastener extends through each of the saddles into engagement with a corresponding end of the core firmly to clamp to side rails against opposed ends of the end rail. The core preferably is of uniform cross-section throughout its length, having edges that internally engage the hollow end rail against lateral movement of the core within the end rail. A resilient washer preferably is captured in compression between each saddle and the opposing end of the core. One of the saddles preferably has an integrally formed extension within one of the side rails for securement of a hinge to the side rail.

Abstract: A frame corner joint includes first and second frame rails having hollow interiors of predetermined contours and ends in mitered abutment. A corner key has legs inserted into the mitered ends of the frame rails. End portions of the legs substantially fill the hollow interiors of the frame rails forming a substantially closed cavity within the frame rails and between the end portions of the corner key legs. Solidified resin foam is disposed within this cavity rigidifying the corner joint, while the remainder of the interiors of the frame rails preferably is substantially free of solidified foam. At least one end portion of at least one leg of the corner key preferably has a flexible wall portion to permit escape of foam from within the cavity in the event of excess foam pressure. The hollow interiors of the frame rails preferably are mirror images of each other, and the legs of the corner key, including the end portions of the legs, preferably are mirror images of each other.