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The role of insulation in electric underfloor heating systems

Insulation plays a vital role in preventing heat loss for electric underfloor heating systems, just as it does in the walls and ceilings of your home. Some people believe the myth that because heat rises there isn't a need to insulate underneath an electric heating system. If this were true, then the sun would do a very poor job of providing warm, radiant sunshine to planet Earth. Heat always goes to cold - always. It is hot air that rises. (I'll provide more information about heat transfer in future blogs).

When electric radiant heating systems are not insulated, the heat can be pulled downwards and outwards from the room. Any unheated rooms that are adjacent to the heated room will rob the heat. Moisture present below a concrete slab can accentuate this thermal loss, resulting in poor efficiency and added expense in heating the area above. To maximize thermal comfort and efficiency, HeatMyFloors.com always recommends insulating under a radiant floor heating system by a ratio of 4 to 1. Although it may prove impossible to get four times more r-value of insulation below a carpeted floor, it's better to have some form of thermal insulation, than none. Concrete floors can have a tremendous pull-down effect on the radiant heat that is intended to go through the finished floor materials. Insulating is a must and will provide a beneficial payback. The challenge is deciding what materials are effective and work well with various finished floors that are available. Slab on grade applications also can pull the radiant heat to the outside edges of the home's foundation. If feasible, insulate the perimeter to prevent growing tulips around your house all year round.

When tile is chosen for the finished floor, HeatMyFloors.com recommends using a 1/4 inch insulated cement board, like ProPanel or Wedi. These offer a thermal break at a decent r-value and are easily bonded to the floor with a thin set.  Check with your supplier to insure these products will work with your system. When carpet or a laminate wood floor is chosen over a concrete slab, we recommend a material called Cerazorb, or a good-quality cork underlayment will work as well. These materials have a higher r-value that will resist heat transfer, which is an even stronger reason to insulate underneath them.

So remember, if you can add insulation, your electric radiant system will perform better regardless of whether it's installed over a heated space. Always insulate over concrete slabs and crawl spaces.

Even though adding insulation on top of a floor can present challenges in the transitions between different flooring types, it will provide a payback on your investment in maximizing comfort. So if you can insulate underneath an electric radiant floor heating system, DO IT.  Your pocketbook will appreciate it.