I am interested in insulating the flooring in my home, however I would like to do so not by installing it under my current parquet flooring, however on the "roof" of my garage (which is directly under the space that needs insulation). Does anyone know if this something that will help improve the heat insulation in the room above? Will it suffice to use regular polystyrene insulation panels or is there any other method that might be more effective? I would like to do so to improve the aesthetic appearance of the roof of my garage as well, as at the moment it is only a concrete splay