Underfloor heating systems

Underfloor heating systems

Underfloor heating is still often seen as something of a luxury, despite being relatively commonplace in specifications. Hot water pipes are laid to a specific design and attached to the floor, then encapsulated by screed. The screed may be chosen specifically to have a low thermal resistance, thereby improving the speed with which the effect of the underfloor heating is felt.

A feature of both low- and high-rise residential construction, underfloor heating is also used in commercial properties and educational buildings. It comes into its own in churches and other historic properties, where sensitive building fabric may not be able to accommodate radiators or other heating sources.

Because the aim is to gain the maximum benefit from underfloor heating, the pipes should be installed on a layer of insulation. The insulation restricts the flow of heat into the floor, improving efficiency, and gives something for the plastic clips, which secure the pipes in position, to be pushed into. An insulation layer used with underfloor heating may therefore fall into one of two categories:

  • Installed above the concrete slab or floor deck and acting as the primary layer of thermal insulation in a ground floor construction. The thickness is determined by the U-value target to be achieved.
  • Providing thermal resistance to the underfloor heating system only, and usually of a nominal thickness (perhaps to achieve a certain level for the floor finish) because the primary thermal insulation layer is below the ground floor slab.

The second of those categories does not apply only to ground floors. In multi-storey residential developments where underfloor heating is provided at every level, there is no U-value to be achieved at the intermediate floors but the heating should be as efficient as possible.

Extruded polystyrene (XPS) insulation boards provide a flat, strong and dimensionally stable base for the floating screed or flooring board, reducing the likelihood of defects in the floor covering or finish. They are therefore ideal to be specified in conjunction with underfloor heating systems, whether at ground floor level or throughout a high-rise development.

Polyfoam XPS Ltd is a leading manufacturer of closed cell, extruded polystyrene insulation. The Polyfoam range is lightweight, strong, moisture resistant and easy to cut and shape, providing thermal performance and strength for the lifetime of the building.

As a bespoke service, where the U-value is achieved by another insulation layer and clipping the underfloor heating pipes is not desirable, pipe layouts can be routed into boards based on supplied CAD drawings.

Recommended Polyfoam XPS products for use with underfloor heating are: