Diagram of a concrete slab floor construction showing position of underfloor heating pipe.

This technique is used when it is necessary to install the pipes before the structure of the building goes up, e.g., if access later would make pouring concrete difficult. Insulation is 50mm minimum flooring grade polystyrene. The heating pipes are attached to the reinforcing mesh using tie wires. The concrete is poured in one operation with the pipes suspended midway. Since the concrete forms a structural slab the thickness should be 150mm (subject to local planning regulations). Response from the heating pipes is slower than with the screed method but the thermal mass is greater.

Concrete Slab Floor Photo

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