Don't Forget to Insulate the Ground!


Insulating a Concrete Slab vs. Heating a Concrete Slab

As we continually try to expand our usable living space in our homes, the basement floor slab becomes part of the conversation. Cold, uninsulated concrete slabs do not create a comfortable living home environment, especially for bare feet. Your feet get cold because you are losing body heat. Socks and slippers help you retain heat, but there are other options to protect your tootsies from the cold and improve the comfort of your concrete slabs, such as insulating the underside of the concrete. Creating inviting concrete floors is possible and can be achieved with the following processes.

What can I do to make my existing concrete floors more comfortable?

  • Install carpet and carpet underlay to isolate your feet from the cold concrete; however, this is not the best process. Moisture could become trapped between the carpet and concrete, which could lead to mold;
  • Install foam board, such as INSTA-PANELS®, Styrofoam SM, or Celfort. Screw plywood on top of the foam board, followed by your flooring. This may be done in conjunction with sleepers. It is best practice to lay poly down to stop moisture from entering the flooring system; however, if your basement floods, moisture will rest on top of the poly under the plywood;
  • Use membrane boards, like DRIcore or DMX, to separate your feet from the concrete and provide a warm and dry surface. Attach wood flooring on top of the membrane boards. Although moisture cannot reach and destroy your flooring system, membrane boards do not provide any major insulation value, especially compared to INSTA-PANELS®, polyisocyanurate board, or expanded or extruded polystyrene.

What should I do with my basement slab for my new home?

  • Insulate the basement concrete slab, prior to pouring, using INSTA-PANELS®, polyisocyanurate board, or expanded or extruded polystyrene. All these products will provide insulation to increase the temperature of your floor slab;
  • Depending on soil conditions, an additional moisture barrier may need to be installed. Moisture barriers typically will provide a good radon gas barrier as well. If radon is present, consult with an expert to vent the slab.

What about heating the concrete slab?

  • For optimal comfort, consider installing radiant-heated concrete slabs because the slabs will maintain your desired temperature;
  • Radiant-heated concrete slabs still need to be insulated. Without insulation, you risk heat loss, defeating the whole purpose of installing radiant heat;
  • The initial cost of radiant heating is more expensive than forced air, and there is an operational cost to the entire system; a heat source, like a boiler or water heater, pumps, and valves all need to be operating and maintained.

What else do I need to know about a warmer, more comfortable concrete floor?

  • Heat moves from hot to cold, and moisture moves with heat;
  • The tighter and better insulated the rest of the building envelope is, the more heat you push into an uninsulated concrete floor;
  • Insulating your home and concrete slab will create a comfortable environment;
  • Insulating your home and your concrete slab will create energy savings.

Increasing the amount of insulation under the floor slab is the best option as there is no operational cost of an additional heating system. The floor temperature will be close or the same as the room temperature in most cases. Besides warm feet and the added comfort of insulating your concrete slab, you can expect great returns on your investment because, as we all know, energy prices are rising, and as they increase so will your savings.