Discovered that the attic access hatch isn’t insulated, which honestly isn’t surprising given when it was built. No ladder system. I’m working on cutting up some foam boards to glue to the backside. Hopefully it will reduce how much is radiated through this barrier.
While touring a rental the other day, I saw someone use what looked like one of those shiny aluminum looking car windshield heat reflectors on the top side of the attic access door. It was a 90+ degree day and the attic access hatch felt room temperature.
Its a good first step, but the r value of reflectix isnt nearly as much as foam board or fiberglass. Foam board has a reflective coating on the outside that will do the same thing (reflecting IR radiation). But if you have some lying around and it works, then it works.
As thick as possible polyiso will probably be your best bet. 1" is R6
Try to get a total of r40.
It would actually be more effective to put the reflective stuff on the under side of the hatch since this would reduce its ability to radiate heat to your space. It would look terrible of course. Actual insulation on the top is going to be the most effective.
That would be a great piece to the full solution. I’m trying to get the R-value to at least 25 (40 being ideal), and the reflective stuff on top or bottom would probably help slow down thermal transfer.