Hi Dave,

I've got a garage access door (32" width) whose wood/aluminum sill
chronically allows leakage beneath it, into the garage when it rains.
I've tried all kinds of caulking, rubber seals, improved drainage, etc
and nothing works - I think it was just a poor installation that needs
to be ripped out.
I'm thinking of replacing it with qwikrete instead of installing another
wood/aluminum sill.

A few years ago I had a door frame that was rotting because water was
leaking around the inside of the frame. Moisture tends to wick up the
bottom of the frame near the sill.

I took the old door frame out and replaced it with a composite frame that
won't rot (I measured my existing door, hinges, locks, etc. and ordered the
frame from Lowes).

Before I installed the new frame, I installed Jamsill flashing in the door
opening. This ensures that any water that finds it's way under the door
frame gets directed outside the building:

http://jamsill.com/

I also used a top quality polyurethane caulk (PL Brand) when installing the
new frame.

Anthony Watson
www.mountainsoftware.com
www.watsondiy.com