1217.9 Joist Systems and Subfloors

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-tocenter for living areas.

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

An air space of not less than 1 inch (25.4 mm) and not more than 3 inches (76 mm) shall be maintained between the top of the insulation and the underside of the floor unless a conductive plate is installed in accordance with manufacturer’s instructions.

Where tubing is installed in panels above or in the subfloor and not embedded in concrete, the floor assembly shall be insulated with not less than R-5 material below the tubing when installed over habitable space.

1217.9.1 Tubing Fasteners. Tubing that is installed within joist spaces and subfloor panel systems shall be fastened according to manufacturer’s instructions. Unless prohibited by the manufacturer, tubing fasteners shall include the following:

(1) Heat transfer panel systems made of wood, aluminum or other thermally conductive materials intended for this application and the specific type of tube.

(2) Staples made of metal or plastic or combination thereof, without sharp edges that would harm tube. intended for this application and the specific type of tube fastened to subfloor.

(3) Plastic rails with integrated tube holders intended for the specific type of tube.

(4) Other fasteners recommended by the manufacturer.