What is an Astragal?

AstragalYou may think you don’t know what an astragal, but you’ve seen them everywhere, from the columns in Greek ruins to a door that closes silently behind you.

An astragal performs many functions. It can be used as the term for the vertical or horizontal bars that separate window panes, or it can be weatherstripping or a rounded wood piece that covers the gap between two doors. On columns, it’s a thin strip with a rounded edge that separates decoration at the top or bottom from the smooth column itself, according to Old Town Home.

Origin of the Term “astragal”

In Greek and Latin, “astragal” means anklebone. In ancient times, most astragals were beaded, which gave them the look of lined-up anklebones.

What an Astragal Looks Like

Today the term “astragal” refers to a piece that’s thick in the center and has a flat strip on either side and a flat back. Traditionally, they’re made of wood. The center is rounded and may have other ornamentation to create visual interest. Modern astragals may be made of metal or other materials and formed in a T shape. When used on an exterior surface, they may be slit, or kerfed, for weatherstripping.

Uses for Astragals

They’re most commonly used on double doors, such as French doors, to seal the gap between components and give the doors a finished look. In addition, astragals may conceal hardware that can latch at top and bottom to keep one of the doors inactive.

A split astragal is the molding used on the active sides of swinging doors to allow movement.

Whether large enough to seal enormous double doors or fine enough to separate tiny panes of glass, they’re a necessary and versatile construction element.

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