I have a metal garage, which I want to insulate to a level of a well insulated house (if that's possible at all). I live in the are where the coldest it gets is about -15 C (5 F) for a couple of weeks, and about +30 C (86 F) for a couple of weeks in summer.
At the moment the garage is insulated with an inch of spray foam from the inside - both walls and ceilings.
Could you advice good but affordable material to insulate it with (walls, ceilings and the floor) from the inside? How thick should that be for such climate?
The garage looks looks as such, the floor is made of concrete:
EDIT: in case anyone will need this in the future, I decided to go for 10cm EPS80 polystyrene foam on the floor, 15cm of rock wool on the walls and roof. The garage will be heated by a 6kW wood burning stove, which should be enough during the cold winter months. If you are interested how this installation would cope with the winter please contact me directly or in the comments.