I have a full set of stairs that walk up into an unfinished attic space. The full sized access door to these stairs is in a hallway as if its a closet. Unfortunately, the max distance I have under each stair before I hit the attic-side of an interior wall (solid blue line in picture below) is only 6 inches. What is the best way to insulate this under the stairs so heat isn't lost from the interior closet pictured? I've drawn a diagram below:

side view of access and stairs up to attic

  • Do you have access to the voids under the stairs? A photo or two would really help here. Details matter.
    – isherwood
    Nov 16 '21 at 22:21
  • I would combine both DMoore's answer and isherwood's answer. Insulating the door to stop cold air from passing the door and falling down the stairs, then an additional layer of insulation inside the closet to protect against any that does get past the door. Belt-and-braces approach.
    – FreeMan
    Nov 17 '21 at 18:43

I'd consider adding 2 inches of foam board to the closet ceiling, then drywall. Finish as desired.


Best way is to add a door at the top to stop airflow and add insulation to that door. On the other side - insulate the door leading up to the attic. There are cheap door insulation kits sold for doors leading to garages... same thing here.

If you don't go the route of stopping drafts I would insulate door and add padding and carpet to stairs. Stairs notoriously let in air. Some cheap carpet would not only insulate but be an air stop.

  • This assumes that the sides of the stairwell are insulated. I suspect they're not.
    – isherwood
    Nov 16 '21 at 22:20
  • @isherwood - yes.. I expect that the basics would be done like just the basic attic insulation. Answer was for more beyond that.
    – DMoore
    Nov 16 '21 at 22:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.