Insulating a steel door

[Corazones]

Our holiday home abroad has a heavy steel stable-type door to the outside - the top is glazed but the bottom is steel sheet. This gets too hot in summer and too cold in winter - an obvious candidate for insulation.
Can anyone suggest what product would be the most efficient without being excessively bulky, easy to secure (preferably with contact adhesive), yet would have an acceptable finish (or be easy to paint)?

 

[freddiemercurystwin]

Some Celotex or Kingspan or similar (not polystyrene), maybe 25mm thick, you would need to frame it inside say a plywood box or similar, to decorate.

 

[Corazones]

Thanks FMT, and a good idea to frame it or I guess the edges would look rough and be easily damaged.

 

[freddiemercurystwin]

There's no insulation that really looks anything like insulation really, insulated plasterboard I guess could be worth looking at eg https://www.insulationshop.co/briti...aline_pir_mr_insulated_plasterboard_38mm.html

 

[Corazones]

Thanks again. I'll have to look in our local builder's merchant and hardware store (we have both nearby in Spain). At least I know what to ask for - tablero aislante - although they both speak a little English!