Using AtticFoil® in Radiant Flooring Over Conditioned Areas
If you are using radiant heat tubes under a floor, then you need a radiant barrier to direct the heat upward into the floor. There are typically two different cases for radiant floors:
- Over a conditioned space. Example: a finished basement or between floors of a home
- Over a non-conditioned (or cold) space. Examples: over a non-heated basement or over a vented crawl space
The install methods are the same for the radiant barrier foil, however over a cold space you will also add traditional insulation to further reduce conductive heat loss.
Using radiant heat is a great method to heat a home. Putting heat into the floor produces a very comfortable source of heat. The challenge is how to most effectively get the heat from the tube into the floor without losing heat below the tubing, i.e. how to get the heat directed UPWARD rather than down into the space below.
This method is typically used in homes that have a heated basement. There is usually no visible insulation between the floor joists when looking up from inside the basement. With this setup, your main goal is to get the heat from the radiant heat tubes to go up into the floor above.
You will simply staple the foil across the floor joists (the ceiling joists from the basement side) and your air gap will be between the radiant tubing and the foil on the bottom of the joists. You will not need regular insulation since the floor is between two living spaces; this is similar to an interior wall assembly: since it is not part of the thermal envelope (the area you heat and cool) no insulation is needed, just a radiant barrier.