Can a steel door in the basement be insulated afterwards?

Hi guys,

I have a standard steel door in the basement, behind it a staircase leading to the garage, located inside the garage. Since my office is in the basement and accordingly temperature-controlled, I usually have almost a 20° temperature difference here.

Question: could I insulate the door afterwards from the outside (i.e., in the stairwell)? For example, by gluing EPS/XPS on it? Does that even make sense?

Thanks, best regards

We have a steel door to our cold attic (uninsulated). I put up a warm curtain.. just with a tension rod.. that already helps enormously!