knuttle writes:

I have a 10 year old shed for my lawn tools, that is 2X constructions,
with standard particle board siding. While the outside was painted
immediately, the inside of the siding was left unpainted. The doors are
basically a sheet of siding with 2x4 around the edge of each door and in
an X pattern in the bottom half of the doors . The doors overlap the
floor joist and come to the bottom of the floor joist. The minimum
clearance under the shed is about 8" and is open on all four sides.

That area between the door and the joist has started to come a part
Since at this time the decomposition is minor, can i stave off the
replacement of the door by gluing the loose particles and painting that
are of the door?

Is there a better solution?

Don't use particle board where it will be exposed to moisture?

I'm not sure the glue will be particularly effective, but a coat
of paint may delay further decomposition of the door.