For the hatch that leads to the roof on the sleeping porch, I was having a hard time figuring out how to best insulate and finish it out.
Things are nearly ready to reveal on the upstairs sleeping porch, but the last major remaining item (other than installing the light fixtures and fan on the ceiling and casing the windows) is figuring out how to insulate and cover the roof access over one of the closets.
I asked for recommendations here on the blog and elsewhere, but I think I had a pretty good solution in that last post.
My only other idea at this point is to insulate around the inside of the opening and the top hatch with 2″ sheathing.
I’d recut that sheathing, cover the inside of the top hatch all the way to the edges where the hatch sits on top of the framing, lay pieces vertically all around the sides of the opening all the way up to the piece on the top, put one 2″ piece on top of the inside hatch, cover everything with drywall, and then just have the lower hatch cover it all up and still be locked with some bolts attached to the trim like I was originally planning.
That’s exactly what I ended up doing. I had enough polyiso sheathing leftover from my ill-conceived idea of stacking it up on top of the hatch cover to knock out this whole project.
I started by cutting a piece of sheathing to put on the inside of the top hatch cover, leaving just enough space so the sheathing runs right up against the edges of the access framing. So that way, when the hatch fits down on the framing, the sheathing forms a seal against the edges of the shaft.
You can see it already in place in the last picture, but next I cut sheathing to layer around the inside of the entire access shaft and then covered it with drywall. You can see the cross-section here of the insulation and drywall filling the shaft.
I came back with four rolls of weatherstripping to seal some of the edges and try to cut down on air leakage everywhere possible. I started with running weatherstripping around the top edge of the framing that faces outward to the roof. So when you set that heavy hatch cover down on top of the framing, it helps to form a seal around the edges of that cover as best as possible.
If you look back at the picture showing the cross section from below (two pictures above) you can see the weatherstripping that I ran around the top edge where the sheathing on the inside of the top hatch meets the sheathing on the inside. So that seals that edge, twice really considering the stuff on the top edge as well.
After that, all that was left to do was finishing the lower hatch cover. I’d already cut and created the hatch cover itself. I used two pieces of plywood to make this, using a smooth piece of sandi-ply for the bottom piece and a plain piece of rough plywood for the top. I wanted it to be thick enough so that when it laid into the opening, it was flush with the trim running around it. I put a little bit of weatherstripping on the inside of the hatch so it seals when it’s pushed up into the opening and locked.
I used some leftover 1×4″ wood to trim out the opening, and then used those little sliding lock bolts for holding the cover in place. With that thick weatherstripping on top of the hatch, you have to push up on it a little bit to get the bolts to line up, which means that there’s tension against the weatherstripping, helping it to form a seal.
And with that, the roof hatch is finished! I painted the hatch itself the same color as the ceiling and it blends in pretty well. Now we’ve got a nice finished access to the roof. Which I think might come in handy in just a couple days on the Fourth when we get up on the roof to watch the fireworks on the Mall downtown.