Floor Coverings

Underfloor heating systems will work efficiently with any floor covering, as long as it is well insulated underneath. However, each covering has different thermal conduction properties. Harder surfaces offer better conductivity and therefore better heat output rates. The following notes provide some guidance on each type of covering.


Carpet and underlay

Suitable for all Polypipe Underfloor Heating Systems.

The nature and thickness of the carpet underlay is fundamental in determining good heat transfer. The most popular underlay type is sponge with a waffle pattern moulded into the underside. These allow good heat transfer. Felt and rubber crumb underlay should be avoided. These products can seriously reduce the effectiveness of an underfloor heating system as they insulate the floor surface and prevent heat transfer. The TOG value of carpet and underlay should be available from the respective manufacturer.

For optimal system performance choose an underlay with a maximum TOG value of approximately 0.5. The maximum TOG value of carpet should be approximately 1.0 to 1.5.


Stone and ceramic tiles, marble or flagstones

Suitable for all Polypipe Underfloor Heating Systems.

These types of floor finishes are usually cold underfoot. However, with floor heating they are transformed into warm, comfortable surfaces. Each of these finishes are essentially brittle and it is imperative that the design of the supporting floor structure is stable and rigid to prevent cracking. It is recommended that flexible adhesives and grout be used.



Suitable for all Polypipe Underfloor Heating Systems.

Sheet vinyl is sensitive to long term exposure to heat. There are two categories of vinyl; one is limited to constant temperatures of around 26°C and the other to 30°C. Check the floor surface temperature indicated by your vinyl supplier for compatibility with underfloor heating. If unsure contact the Polypipe hotline or the vinyl floor manufacturer.



Suitable for all Polypipe Underfloor Heating Systems.

Laminate flooring should be laid on roll type floor leveller, rather than the rigid panel type. Movement that occurs must be accommodated by an expansion gap around the floor deck.



Suitable for all Polypipe Underfloor Heating systems.

However, care should be taken to ensure that the moisture content of the product is less than 10%. When using a solid floor system it is essential to ensure that the screed or concrete floor has completely dried out prior to the timber floor covering being laid. It is also advisable to run the underfloor heating system for at least two weeks before the floor is laid. With natural timber products it is also advised that the flooring be allowed to acclimatise to the environmental conditions of the room before installation.

When using a timber floor covering on a suspended floor construction it is vital that the intended product is classed as a ‘structural’ floor application.

If so, this product can be laid directly on top of the joists. If this is not the case then an additional layer of 20mm/22mm timber layer will first need to be fitted and this could seriously compromise the performance of the underfloor heating system.

With all timber floor applications it is important to ensure that the floor surface temperature does not exceed 27°C. Therefore, care should be taken when designing the underfloor heating system to

ensure that this parameter is met. Before choosing or installing your timber floor covering we would strongly recommend that you seek the guidance of the specialist timber flooring supplier/contractor to confirm the suitability of the product.

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