Sealing 4"x4" hole in roof?
My friend and I just cut a 4x4 hole in the roof of his bus in order to put a ladder onto the platform we built on top. The original way we tried would not work and I was hoping for some ideas. Our goal is to be able to have the cover removable but still weather proof. The ceiling is a double walled sheet metal. The hole is off set to the side of the roof where there is a slight curve. We were hoping to use wood and a sealer but maybe we just had the wrong technique. Most of the wet seasons it will be stored under a tarp but there is always the chance of rain where we live. (Portland, Or) We need the frame to be solid enough to accommodate many people going in and out. If needed, I have pictures.
Thanks so much cause we are needing some good advise,