1217.6 Poured Floor Systems (Thermal Mass)

Where tubing is embedded in a concrete slab such tubes shall not be larger in outside dimension than one-third of the overall thickness of the slab and shall be spaced not less than three diameters on center. The top of the tubing shall be embedded in the slab not less than 2 inches (51 mm) below the surface.

Where embedded in or installed under a concrete slab, tubing shall be protected from damage at penetrations of the slab with a protective pipe sleeve. The space between the tubing and sleeve shall be sealed. The tubing at the location of an expansion joint in a concrete slab shall be encased in a protective pipe sleeve that covers the tubing not less than 12 inches (305 mm) on either side of the expansion joint or the tubing shall be installed below the slab.

Where a poured concrete radiant floor system is installed in contact with the soil, not less than R-5 insulation shall be installed and shall be placed between the soil and the concrete; extend to the outside edges of the concrete; and be placed on all slab edges.

    Where a poured concrete radiant floor system is installed on grade, not less than R-5 insulation shall be installed and placed on vertical slab edges.

    Where a poured concrete radiant floor system is installed within a habitable space above and below, the total R-value of the floor system below the concrete slab shall be more than the total R-value of the material lying above the concrete slab and the floor system shall have not less than a R-3 value.

Where tubing is installed below a subfloor, the tube spacing shall be in accordance with the system design and joist space limitations.

    Where tubing is installed above or in the subfloor, the tube spacing shall not exceed 12 inches (305 mm) center-to-center for living areas.

    Where tubing is installed in the joist cavity, the cavity shall be insulated with not less than R-12 material.

    An air space of not less than 2 inches (51 mm) shall be maintained between the top of the insulation and the underside of the floor unless a conductive plate is installed.

    Where tubing is installed above or in the subfloor and not embedded in concrete, the floor assembly shall be insulated with not less than R-12 material below the tubing.

Where piping is installed in the wall stud cavity or the ceiling joist cavity, the cavity shall be insulated with not less than R-12 material. The insulation shall be installed in such a manner as to prevent heating or cooling loss from the space intended to be controlled.

    An air space of not less than 2 inches (51 mm) shall be maintained between the insulation and the interior surface of the panel unless a conductive plate is installed.