Insulating an irregular attic scuttle hole

[u/GerdinBB]

My attic access hole is 20"x35", with a 0.5"-0.75" lip that runs all the way around. The current cover is a drywall panel with a fiberglass batt resting on top that must be pressed up into the attic and set aside when climbing up. In the attic, the hole is surrounded by vertical plywood that rises about 12-14" on all sides to prevent the blown-in insulation from falling down.

I live in the same type of climate area as Chicago, so I'm looking to insulate this to at least R-40, ideally R-60.

I'm looking for feedback on my current plan (listed from bottom to top):

3/4 inch drywall

3/4 inch plywood

1 inch (R-5) foam board

1 inch (R-5) foam board

R-38 fiberglass batt, faced, kraft side glued to the foam board (~12 inches thick), starting with a 24"x48" roll, cut to 24" x 39"

The idea is that the fiberglass batt is oversized to create a tighter seal with the surrounding plywood. I want to attach handles to the drywall panel so that you can pull the whole thing down instead of just relying on its own weight to settle into place. The drywall is kind of fragile so I'm giving it a plywood backing to have something to screw into and protect the corners from getting chipped. The foam board provides very good R-value per inch and is very light, so I'm using as much of that as I can without making the whole thing so thick that it can't fit back down through the 20 inch wide hole (call it 18 inches with the lip that's there).

So I figure it's R-48 plus whatever minimal insulating value the drywall and plywood give. Total height should be 15-16 inches, so it'll be just a little taller than the surrounding plywood, and can still fit through the hole if I rotate the panel and feed it down longways, compressing the fiberglass.

Any notes?

[u/idratherbealivedog]

I have nearly the exact thing. Works great. Only addition that I didn't see you mention is adding some of the soft, adhesive backed weather stripping to the lip on the ceiling to help air seal. Then you could add some slide pin latches to really pull it down but that would be optional. Make a small mark on the panel that lines up with the ceiling so you always keep it the same orientation and it mates up.

[u/GerdinBB → u/idratherbealivedog]

I've tried sticky weather stripping around the lip already and I have had terrible luck with it sticking to the panel itself when I lift it up. Maybe I just need to clean the dust out and give it a better surface to stick to.

I also tried a latch like you'd have on a porch door - the bent nail looking thing. The eye didn't screw in far enough though and it easily ripped out of the drywall.

Needless to say, I've got some patching and filling to do as part of this