We just bought a townhouse and found out about an issue I need help with.
There is a french door on the middle level, leading out to the deck. It is about 17 years old, and the threshold is rotten/wobbly on one side. In the finished basement directly below this door, the sheetrock registers 40% moisture when checked with a moisture tool. The 40% moisture area is directly below the wobbly threshold area.
There are some problems with the flashing/siding at the bottom of the door. From what I have read, the problem could be the threshold/door itself, the flashing at the top of the door, or the bottom.
We had this exact same problem in my last townhouse. We had to install a new french door, perform subfloor repair, etc. What a disaster!
Is there any way to tell what the root cause is? I'd really like to know if it is the flashing/siding, or just that the threshold is shot from age and leaking water down through the wall.
Thanks so much, I hate this issue and have already lived through it once.