Patent ID: 7748194

Claim:
A closure assembly that includes: a frame having at least one hollow end rail and a pair of side rails coupled to opposed ends of said end rail in butt joints that include: a core extending through said hollow end rail, and from opposed ends of said end rail through openings in said side rails into interiors of said side rails, a saddle within the interior of each said side rail straddling a corresponding end of said core, and a fastener extending through each of said saddles into engagement with a corresponding end of said core firmly to clamp said saddles against inside surfaces of said side rails and thereby clamp said side rails to opposed ends of said end rail, wherein said core is of uniform cross-section throughout its length, including end portions of said core that extend from opposite ends of said end rail through openings in said side rails, said cross-section having edges that internally engage said hollow end rail against lateral movement of said core within said end rail, said cross-section of said core having openings at opposed ends of said core for receiving said fasteners from a direction lengthwise of said core.