RD wrote:
I've recently discovered a moisture problem under my front door. It
is
only visible from the basement. The sill plate and joists that sit
atop my concrete foundation wall and directly below my front door are
moist during rainstorms. There does not appear to be any evidence of
moisture stains or damage to the plywood subfloor around the door. I
suspect that water is making contact with the framing under my front
concrete step and then wicking in. I'd like to fix before I have
serious problems. My home is 4 years old.

Has anyone else seen this? Any advise on how to repair?

Thanks,
RD

This is a common problem.
The solution is not cheap, but will save long term deterioration of the
frame.
Install a pan flashing below the door.
Also look at the conditions around the door that might promote extra
water and splashing.
TB