This project shows how to replace the exterior french door t-astragal (or simply astragal). An astragal is the moulding attached to the inactive door that contains the slide bolts, strike plate and weatherstrip to seal.
The new french door t-astragal is highlighted in this photo:
This is the interior view of the French doors and the new t-astragal:
This set of French Doors were in need of several repairs. So far I’ve replaced the door hinges and weatherstrip. Replacing the split and bent astragal will complete the overhaul.
Broken French Door Astragal
The bottom end of the exterior door astragal is bowed outward causing a gap in the weather stripping. The white section of stick-on weatherstripping (red arrow) was added by the prior homeowner in an attempt to seal the gap.
The problem with the original wood astragal has split around the bottom slide bolt (also called a ‘flush bolt’). The t-astragal slide bolt design is poor (as you will see in the following photos) because it was only a matter of time before the wood split due when active door closes and bumps against the astragal:
How to Replace an Exterior French Door Astragal
The following steps show to remove the wood astragal and install a new aluminum astragal.
The inactive French door to which the astragal is attached is removed by tapping out the hinge pins and the door is taken to the workshop. See this article for details on how to remove a door.
The exterior French door is in a pair of jigs made from scrap 2×4 blocks with the astragal side up. This is a view of the door bottom:
The wood astragal around the slide bolt is clearly visible in the next photo. The slide bolt fits in a U shaped mortise. Each time the door closes, the slide bolt levers sideways in the mortise as the bolt hits the threshold, causing the astragal to split. The slide bolt is made of two metal halves that are held together by the mortise, so it separates as the wood splits. A very poor design that was destined to fail in my opinion.
Here’s the bottom view of the split t-astragal. The red lines highlight how the wood astragal split and bent outward in the direction of the arrow.
The top of the astragal and door is shown below. The fine red line (click on the image for a full size view) delineates the astragal from the door body. This door has a metal skin whose edges are folded over a wood door frame.
This project is continued in How to Replace an Exterior French Door Astragal – Part 2.
Take care,
Bob Jackson
