Wind driven rain runs down the outside of a door to the threshold
where it is supposed to flow down and off without entering the house.
Unfortunately this is not always the case. Some finds it's way in
around the door edges and weatherstripping. If it can't run in
directly it may wick in through the smallest cracks.

I believe this is a common problem that many people are unaware of
because water soaks in under the flooring around the threshold and
goes unnoticed until the problem becomes a major one.

Two of my neighbors have the same problem. By the way we are all
building are own houses and are living ln them as they are being
completed. I found and corrected a few problems that would not have
been very visible once the finishing had been completed.

After a few unsuccessful attempts to stop the water leaking in, I
ended up installing storm doors on all my outside doors. Not a drop
of water on the floor after that.

Yep, we had the same problem with the entry doors of our old mobile home.
No amount of caulking would prevent the leaking, but a storm door did stop
the water.

Unfortunately, for a variety of reasons I do not want storm doors on the
doors that are leaking. Especially for the garage and back doors where
we're often hauling large objects in and out. My in-laws just splurged on
a decorative door and don't want to cover it with a storm door.

Anthony