I'm finishing a storage room in my house. General layout, room is 12' x 12', door on one wall, window on opposite wall, roof peak ~12' above the axis between the door and the window. Roof slopes down to either side, so the side walls of the room are about 6' tall, at which height they intersect the slope of the roof.

Now, there's about 4' of space between the side walls of the room and the exterior walls of the house. I want to use this as accessible storage. That means I need doors between the room I'm finishing and these unconditioned spaces. Wall studs are on 24" spacing, and they hold up the roof trusses, so I'm not comfortable removing one. That means the maximum dimensions of these doors are maybe 68" tall and 22" wide. This is obviously not a standard door size.

I could build a custom hinged door, but I'm considering building a custom barn door instead, both for aesthetics and for looser tolerances in the build and install. Thus my question: is it possible to seal an interior barn door to provide an acceptable level of insulation between a conditioned and an unconditioned space?

  • 1
    It might be a good idea to quantify acceptable so its can get subjective answers
    – Ack
    Apr 10, 2020 at 2:15
  • 3
    Possible, sure. How much effort/expense, and is this effort/expense justified .vs. just conditioning the whole space by moving the insulation/envelope out so you don't need to get nutty with doors and they can be normal uninsulated unsealed doors opening to a storage area that's not well-conditioned compared ot the room, but is not an intrusion of the unconditioned exterior into the space separated only by these doors, that then have to be fabulously insulated and sealed as well as being doors... Not a winning plan given that even good doors are poorly insulated .vs. a normal wall.
    – Ecnerwal
    Apr 10, 2020 at 2:37

2 Answers 2


I'm sure it's possible but it sounds like a real mission. sliding doors tend to seal much worse than swing doors but if you're prepared to make a heroic effort and embrace tighter tolerances instead of looser something could probably be done.

For a swing door, 20" is a standard door width but you'd need to cut the height down and repair the cut end, https://www.youtube.com/watch?v=iSLiWCgCATE

I clamp a straight-edge to the door because I'm not very good at cutting straight lines.


Yes you can seal a sliding door. we do this with garage doors also a wide rubber flap attached to the door frame that “seals” the door will work the seal is not perfect but works quite well. If you try to seal things two tight the door won’t slide easily but I have put the strips on the door at the bottom on the frame at top and side and this eliminated most of the air movement and some noise.

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