During some renovations to my house and I removed some wood-paneling and uncovered an exterior door. The door faces west, so it gets the late afternoon sun and in Phoenix, the door gets hot.

Typically, I wouldn't be concerned about an exterior door but it's a hollow core door which lets in a lot of heat. I can't afford to replace the door with something that is solid, yet, so I'm trying to figure out a way to provide a bit of insulation to it.

The door looks like this:

enter image description here

While we will not be using to enter/exit the house at this time, we'd prefer to leave the door somewhat accessible. This is eventually going to be the main entry door into the house, but if we aren't able to insulate it at this time as is, then we'd consider covering it again.

Since it's hollow core, I know it has the honeycomb interior so using spray foam would be really difficult.

I was thinking about purchasing some rigid insulation foam board, attaching it to the door, then attaching a piece of wood on top of it. My reasoning is that it would give a bit more protection from the heat of the summer and the cold in the winter.

Does anyone have suggestions on how I could insulate this door?

  • Drill lots of holes in the interior side of the door and get yourself some cans of expanding foam and start filling 👍
    – Weare138
    Feb 16 at 3:38

1 Answer 1


I think you've hit on the easiest solution. Putting in a layer of insulation board and then boarding over the top of that is the approach I'd take.

If you don't want to use the door then you can just put insulation right to the frame and board over that to hide the door completely. However, if you want to be able to use the door then you'd have to leave enough space at the edges so that the door could open without catching on the frame.

Insulation board is quite light so you'll probably be able to glue a frame to the door an inch or so in from the sides and then put the insulation in that. A piece of hardboard glued or tacked over the top will keep the board in place. This will mean that there is still some heat leakage around the sides but nowhere near as much as through the entire door.

  • Ideally, I wouldn't completely cover the entire doorway. We'd like to be able to enter/exit through it until this project is completely over which won't be for a little while. Covering it completely will be the last resort if needed. :(
    – Taryn
    Aug 22, 2015 at 16:09
  • @bluefeet - ah. I misunderstood, but you did say you wouldn't care if you couldn't open the door ;)
    – ChrisF
    Aug 22, 2015 at 16:11
  • Yes, I did say that. I clarified my question a bit. I've no problem considering covering it, if we have no other options. The long-term plan is to make this the main entry door into the house so the preference would be to not cover it again.
    – Taryn
    Aug 22, 2015 at 16:15

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