Radiant Floor Heating Concrete Slab Insulation

Radiant tubing was at the bottom of the slab in this area more than seven inches down in the concrete and set atop the foam sub slab insulation.

Radiant floor heating concrete slab insulation. How much insulation is necessary under a typical radiant slab. When the thermal mass of the concrete is heated the warm slab acts as a radiator distributing even heat throughout the structure. The insulation phase is crucial for a radiant floor. Our photo above on this page shows that tubing was in some sections more than 18 deep and adjacent to a large area where sub slab insulation was simply omitted by the contractor.

The system works via pex pipe a small pump a water heater and a thermostat. Radiant heat insulation is installed to prevent heat loss from a pex radiant floor heating system most commonly pex embedded in concrete slab or stapled underneath the plywood subfloor. Slabs that include embedded hydronic tubing for radiant heat always need a continuous layer of horizontal insulation under the entire slab. Different insulation types help to minimize heat loss from convection air circulation conduction direct contact or radiation energy waves modes of heat transfer.

Mainly heated slabs radiate outward rather than downward so insulation on the edges of the slab is most important. The picture above shows a concrete floor we re about to pour with radiant heating tubes installed. The concrete was 4 thick and the insulation under the slab was 2 thick. 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.

Insulationstop is the best source for top quality products at the best price. In a heated floor slab heat losses into the ground and outward through the edges of the slab and foundation wall are quite significant. 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. Any cooler surface in contact with the slab will try to steal its heat.

Remember that your slab will be about 75 degrees f. 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. This is about installing hydronic radiant floor heating in a slab floor system. Our photo above shows a well designed insulated radiant heated concrete slab with an insulated foundation perimeter being installed in two harbors minnesota in 2007.

Need insulation for under concrete slabs slabs with radiant heat.