Reflective insulation requires airspace between the material and what you are trying to insulate. In other words by rolling out the reflective insulation on the floor and rolling carpet on top you are creating a totally conductive environment. Conductive transference occurs when two surfaces are sandwiched. Remember heat seeks cold. To stop the effect you need a thermal break. Thermal breaks require a trapped airspace on one side and air movement on the other side; by stapling your reflective material to the bottom side of your crawl space you are effectively stopping the transference of heat to cold or cold to heat. There are many different types of reflective insulations to choose from and some are better than others because of the materials used in their construction.

If you want to put something under the carper I would suggest placing a non-conductive material such as a product that consists of a polyethylene 3mill covering EPS (Extruded PolyStyrene) core and another 3 mill backing. Call me @ 602 528-3645 and I can explain in better detail and let you know where to get these products.

Good Luck

Dan Biermann

sales@microfoil.com is my e-mail and my web site is microfoil.com