A corner assembly for interconnecting first and second frame members. A first plate member includes an outer face having a mounting rail projecting therefrom which is receivable in a slot in the first frame member and a bolt-receiving bore therethrough extending along a first axis at an acute angle to the outer face. A second plate member includes an outer face generally perpendicular to the outer face of the first plate member and having a mounting rail projecting therefrom which is receivable in a slot in a second frame member. The second plate member including a bolt-receiving bore therethrough extending along a second axis at an acute angle to the outer face of the second plate member. A central portion interconnects the first and second plate members and has a mounting surface and a bore extending therethrough. The mounting surface including an alignment rail projecting therefrom. A corner has a first sidewall configured to abut a terminal end of the first frame member, a second sidewall configured to abut a terminal end of the second frame member, and a mounting wall having a slot therein adapted for receiving the alignment rail of the central portion.