I am in a rental guest house that has a sunroom (I mention rental as I don't want to spend a lot of money) with sliding glass doors on all sides (4). The floor of this sunroom is brick - never damp and the walls between all doors are insulated. There is currently no heat in this room and I'm in a 4 season climate and would like to put something over the brick to utilize the room for more than I am currently i.e. sitting/sunroom, work out space. A friend suggested a dense foam that might have a silver barrier on it to retain heat and repel cold and wondering if anyone has heard of something I can use. There isn't a lot of clearance in the door area into the main living area - probably 3/4" tops. I would like to put a rug or covering over this insulation that has no environmental impact (fumes etc). I welcome your suggestions.
hot moves to cold... nothing "repels" cold. Insulation resists thermal transmittance. Now that we have the tags established you can address your needs. First insulation for what reason? Floor is not wet but is it cold? It should not be. The mass of the brick absorbs heat during the day and stores it as latent energy. At night the warm brick will release this heat to the colder surfaces of the room as radiant heat. (cold objects will attract the energy from the hotter objects and transmit this energy by infrared rays.) So for you this is all a good thing.
Possible solution is to use 3/8" plywood a good carpet pad and carpet.