There is a 3'x3' opening in the ceiling of my second (top) floor. The opening leads into the unheated attic. I want to both seal and insulate this opening to keep out the cold in the winter. (I live in New York, were it can get cold.) I already have built a box around the fan in the attic using hard pink insulation, But it does not seal perfectly and is not all that well insulated.

How might I secure a 2"x3'x3' box to the underside of the opening (i.e., in my second floor hallway)? The box would contain 1.5" hard, pink insulation in this box and would have a 1/2" cover framed with 1"x2".

How might I attach this to the ceiling so that it will be a tight fit but easy to take off in the spring?


P.S. These related posts do not cover this question. How do I insulate a whole-house fan during the winter?
Air sealing a whole house fan

Here are photos of the vent opening and fan.
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  • If that louver is steel I'd look at using magnetic tape. – isherwood Nov 29 '17 at 17:19
  • @isherwood I've used a sheet of plastic in the past. That ended drafts but provides zero insulation. – Yehuda_NYC Nov 29 '17 at 17:38
  • 2
    I'm not sure what you're saying to me. Build your foam panel and attach it with magnets. – isherwood Nov 29 '17 at 19:02
  • Magnets might be strong enough to support a foam panel. I was thinking of putting the foam in a wooden box, which would weigh too much. But your idea seems practical. Thx. – Yehuda_NYC Nov 29 '17 at 19:04
  • The reviews of magnetic tapes on amazon are lukewarm. Is there a style that has good holding power? – Yehuda_NYC Nov 30 '17 at 21:25

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