Why do Class C's always leak in the front upper bunk area?

Howdy, I agree with all above about inherent class C leaking. I have experienced all discussed here. I wish my current one did not have a window but it had many other disirable features.. I once vowed not to get another class C until I had a covered place to keep it. But alas I found a Winnie and could not wait. Hoping to build a 12' high lean to as soon as I can.