: Any idea how thick the insulation has to be? It will be a temporary shop, so
: I don´t want to spend more than necessary. I plan to sell the container
: again when I´m done building.

: Palle Dam

Hi Palle,
I'd use 50mm at least, if you'll be building over the winter. That would be comfortable here in Ireland but it rarely goes much below freezing here. In Denmark, you might neeed a bit more heating.
You may be able to get a return on the insulation if it isn't damaged when you're finished building. Though insulation isn't too expensive and it can be very handy to have 'spare'.

A section of old carpet helps with the floor. Make sure it's old carpet as it will be 'ruined' with saw dust, etc.

As Deano posted a peaked, or sloped roof (removable and recyclable) added to the container would help shed water and keep any snow from accumulating on the container and lower any heat loss.

If you do it right, you could permanently insulate and fit out the container and sell it as a mobile workshop.

Mike Savage
South West Cork