Most rolloff roof observatory designs have a “flippy board” feature that flips up before rolling the roof off. This allows for clearance of any instruments you may have inside, and covers the gap when the roof is closed, where the roof meets the wall.

In the past, when we had a metal roof, we used a large flippy board (ie very tall) as the roof span was 10′ and the roof integrity was such that it did in fact sag. Especially when loaded down with wet snow.
So we needed a larger clearance. When the roof blew off and was replaced with this wooden roof in 2018, we reused as much as we could including this flippy board made of 3/8″ plywood, with some 1×4’s as stiffening, in an 8′ section and a 2′ section.

We know.. a recipe for disaster/failure. Well, three years later, the flippy board has to go. It had warped so much that it did not keep out the weather in many places.

So, off it came and we decided upon building up the wall section to meet the roof with a small a clearance as possible. Since the new wooden roof was much stronger, and showed now signs of sag at all, we aimed for a 1/4″ clearance between roof and wall.

It was built from a 5/4″x6″ cedar board that came from the old metal roof skirt. Being a little short, two pieces were made and attached. In addition, a 1×4″ was mounted on the roof section to provide a nailing surface that stuck out a bit for the weatherstripping cover we would add later, also scavenged from the flippy board. This is the final part, old lawn edging attached and covering the 1/4 to 1/2″ gap. It turned out to be a little inflexible, so slits were cut vertically in it from the bottom, every foot or so. Now it closes without too much force.
The first weather test was the snow and rain we received a few days later… so far, no snow or rain inside!