During very heavy rain today we noticed a large pool of water gather around the base of the back door, on the inside. It's an external door with a glass center. I found that the door was actually 'weeping' from the point where the wood frame of the glass meets the door. I expected to see water inside the double paned glass but it's dry. Where is this water coming from? I couldn't see any obvious holes or cracks on the outside of the door. Could water be getting into the door (the wooden frame part maybe) and leaking out through this area? After a few hours of heavy rain there was enough water on the floor for three towels to soak up.
Thanks.