Underfloor heating systems

Underfloor heating systems

Underfloor heating (UFH) remains something of a luxury, despite being relatively commonplace in specifications. Hot water pipes are laid to a specific design and encapsulated by screed. The screed may be chosen specifically to have a low thermal resistance, 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 radiators or other heating sources may not be sensitive to the building design.

What thickness of insulation should I use with underfloor heating?

Because the aim is to gain the maximum benefit from underfloor heating, pipes should be installed on a layer of thermal insulation. The insulation restricts the downward flow of heat into the floor, improving efficiency, and holds the plastic clips that secure the pipes in position.

An insulation layer used with underfloor heating may fall into one of two categories:

  • Installed above a floor slab or suspended 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). In this case, the primary thermal insulation layer is elsewhere in the ground floor construction, usually below the concrete slab.

The second category 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 still needs to work efficiently.

Extruded polystyrene (XPS) insulation boards provide a flat, strong and dimensionally stable base for fixing the pipes and reduce the likelihood of defects in the screed or floor finish. They are therefore ideal to be specified at ground floor level or throughout a high-rise development.

What Polyfoam XPS products are suitable to use with UFH?

In domestic properties, Polyfoam Floorboard Standard is the perfect choice for the relatively low loads imposed. For larger domestic-type buildings, as well as office and commercial developments, featuring underfloor heating, Polyfoam Floorboard Extra offers the same thermal efficiency, and a higher compressive strength to bear the load of a denser screed and a more intensive building use.

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. Product benefits include:

  • High compressive strength.
  • Highly resistant to water absorption.
  • Robust and can tolerate traffic from following trades.
  • Environmental Product Declaration.
  • BES 6001: Responsible Sourcing of Construction Products.

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. For more information about this service, contact us with details of your project.