Concrete Slab Insulation For Radiant Heat

Crete heat r 6 or r 10.

Concrete slab insulation for radiant heat.

Remember that your slab will be about 75 degrees f. Slabs that include embedded hydronic tubing for radiant heat always need a continuous layer of horizontal insulation under the entire slab. The system works via pex pipe a small pump a water heater and a thermostat. Many increase the under slab insulating foam board thickness to 3 or 4 inches at the outer 2 to 4 feet of the slab.

Any cooler surface in contact with the slab will try to steal its heat. How much insulation is necessary under a typical radiant slab. If you re pouring up against your foundation walls insulate between the slab and the walls. In cold climates it is advisable to use a minimum of 2 inches of extruded polystyrene under the slab.

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. We stock rfoil and crete heat insulation brands for use in concrete slab and between the joists pex radiant heating installations. The concrete was 4 thick and the insulation under the slab was 2 thick. Rfoil 2222 series reflective r 13 0.

When the thermal mass of the concrete is heated the warm slab acts as a radiator distributing even heat throughout the structure. 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. Mainly heated slabs radiate outward rather than downward so insulation on the edges of the slab is most important. Downward heat loss from a radiant slab should not exceed 10 percent of upward heat output a ratio derived from european installation standards for floor heating systems.

John siegenthaler a consulting engineer who specializes in hydronic heating system design responds. Designers generally insulate both directly under the slab and around the perimeter as well. Because heat goes to colder areas radiant floor insulation is almost all the time placed under the heating element often the concrete slab. Need insulation for under concrete slabs slabs with radiant heat.

The foil within the product acts to spread out the heat signature of the heating coils. 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. Rfoil ultra cbf r 3 8 and underpad r 1 1. The picture above shows a concrete floor we re about to pour with radiant heating tubes installed.

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.