I have a roughly 5x8 ft mudroom. Walls and ceiling have 3 inches closed cell spray foam (~R 21). Has a weather striped steel door to outdoors and a new solid pine door to the kitchen. That pine door has a cat door. No baseboard hot water/gas heat in that room, but woodstove heats house 95% of season. The floor is the problem. All I've got are original planks (1920) with gaps, then particle board (I think) with linoleum stick tiles that I put on 2 years ago. I know it is not a heated space, but the floor cold is killing me. I'd like more of a buffer zone between the elements and the kitchen. I seem to lose a lot of heat through that cat door. There is space to add a couple of inches to the floor without affecting door swing. I'd rather not tear up the floor, but add to it's height. If I could get a good air seal and R 4-5, do you think that would make a difference? Research led me to a few options that leaves the linoleum and lets me build on top of it. Material cost is not much of an issue since it is such a small space. a) Rosin paper, then cork flooring (~R2), then carpet underlayment (~R1), with short carpet on top (~R1). b) Dricore subfloor, then carpet underlayment, then carpet. Other suggestions are welcome. Thanks.