Concrete Slab Insulation For Radiant Heat

The picture above shows a concrete floor we re about to pour with radiant heating tubes installed.

Concrete slab insulation for radiant heat.

If your slab is heated it s a good idea to increase the r value of the vertical and the horizontal insulation to at least r 20. We stock rfoil and crete heat insulation brands for use in concrete slab and between the joists pex radiant heating installations. Any cooler surface in contact with the slab will try to steal its heat. The reflectix concrete slab insulation is an innovative easy to handle product that increases the energy efficiency of radiant floor and snow melt systems under concrete.

When the thermal mass of the concrete is heated the warm slab acts as a radiator distributing even heat throughout the structure. Designers generally insulate both directly under the slab and around the perimeter as well. The foil within the product acts to spread out the heat signature of the heating coils. If you re pouring up against your foundation walls insulate between the slab and the walls.

Insulationstop is the best source for top quality products at the best price. The concrete was 4 thick and the insulation under the slab was 2 thick. The system works via pex pipe a small pump a water heater and a thermostat. In cold climates it is advisable to use a minimum of 2 inches of extruded polystyrene under the slab.

John siegenthaler a consulting engineer who specializes in hydronic heating system design responds. While it was done as a new house was being built in my last house i poured a concrete floor on top of a wood framed floor system and could have put radiant heat in that as well. Mainly heated slabs radiate outward rather than downward so insulation on the edges of the slab is most important. It serves on top of those purposes mentioned above also as protection for the concrete slab itself and prevent its earlier disintegration due to oxidation from soil gases and chemicals.

It s possible to calculate the r value needed to meet this goal while accounting for such factors as floor coverings soil temperature and required upward. Crete heat r 6 or r 10. Rfoil ultra cbf r 3 8 and underpad r 1 1. Slabs that include embedded hydronic tubing for radiant heat always need a continuous layer of horizontal insulation under the entire slab.

Rfoil 2222 series reflective r 13 0. How much insulation is necessary under a typical radiant slab. Many increase the under slab insulating foam board thickness to 3 or 4 inches at the outer 2 to 4 feet of the slab. Remember that your slab will be about 75 degrees f.

Need insulation for under concrete slabs slabs with radiant heat.