I am converting a detached garage to be used as a gym/summerhouse and maybe in the distant future it could be used as an office but that is not definite. It isn't a habitable room and doesn't need BC approval. Windows/doors will bricked up or double glazed. I am insulating the walls and ceiling with 70-100mm Celotex. The base is concrete and I hadn't considered insulating up until now. My question is how much benefit I would get from insulating the floor? Would I see a significant increase? The room will not be completely empty, so I wanted to avoid doing work to the floor (apart from floor tiles at the end), but if the recommendation is to insulate then I will have to work around this.