This is a self-build Conservatory about 10 years old. I have had a small leak from the start, where it butts the Building and it comes through where the Leg is, on the inside. I have had 2 different roofers work at it but they could not stop it. There is Flashband & Roofing Seal over the Joint, and still it comes in. I can soak it with a Hosepipe, leave it, soak it again, and nothing will come through, but get a drop of rain..........but not everytime.......so suggest to me it must be directional....wall is ruined....any ideas?