wood flooring advice


Underfloor Heating Installation Guide

Underfloor Heating Installation

When installing wood flooring over an Underfloor Heating System, installers/specifiers should consider the wide ranging temperatures which will influence movement. During the summer months the timber will expand whereas during the winter, when the heating is switched on, the timber will shrink.

Only wood flooring specifically approved for use over radiant heat should be used, this may be approved engineered boards or some types of solid overlay. Installing flooring which is not approved over a radiant heat source will void any product warranty and may result in damage to the floor. It is also vital to understand that the surface temperature of the new timber floor should not exceed 27°c (81°f); otherwise excessive gaping between boards and/or cracking of the top layer may occur. For wider hardwood boards, which are more susceptible to changes in moisture, a maximum surface temperature of between 22° - 24°c (72° - 75°f) would be appropriate.

Its is usually sufficient to provide a comfortable environment in newly built properties with adequate insulation and is generally brought about, in water feed systems, by a water circulation temperature of 35° - 45°c (95° - 113°f) or, in Electric systems, with temperatures equates to an average power output of approximately 100W/m2. It is important to note that the exact heat output will vary according to the thermal conductivity and resistance of the system and floor covering used (species, thickness etc) therefore it is important that a dedicated thermostat is installed at floor surface level to allow the temperature to be accurately controlled.

Unless otherwise advised by the Underfloor heating manufacturer, pipes and cabling must be evenly laid-out. Water pipes are usually spaced at no more than 300mm centres and Electric matting should be laid evenly, on a levelled subfloor, throughout the floor area in order to avoid local 'hotspots'. When underfloor heating systems are installed at ground or basement floor level (lowest level of property), the heating elements are usually covered beneath a screed and the recommended depth of the screed may vary between 30mm and 75mm, while deeper screeds will aid in heat dissipation and will help prevent local hotspots from occurring. Allow the screed sufficient time to fully dry and ensure that the equilibrium relative humidity is certainly no more than 75%RH but ideally no greater than 65%RH. Screed and room moisture levels should be recorded in the Heat-Up Protocol Documentation prior to timber installation.

Once the heating system is installed, and before any wood flooring is laid, the heating system should be turned on gradually in maximum 5°c (41°f) increments a day and should be run at half to two-thirds its maximum power for two weeks, followed by maximum power for 2 - 7 days prior to installation of the flooring. The room should be ventilated briefly every day during this period.

The underfloor heating is generally switched off when laying the floor in order to prevent moisture being driven to the underside of the boards. Whilst this is not strictly necessary in the case of nailed or floating system, it is especially true when stick-down systems are installed. For floor installation guidelines please refer to our 'Wood Floor Installation Guide', available online at www.ecora.co.uk. After the floor has been installed, the heating should be turned back on very gradually over a period of several days. Sudden changes in temperature such as testing period should be avoided as this can 'shock' the timber and cause rapid irreversible setting of the wood.

It is not advisable to cover the timber floor with insulating materials like protective sheeting, carpets or rugs when the heating is operational as it may create local 'hotspots' and compromise the timber, glue and/or finish. 

The information provided here should be used as guidelines only. No warranty or guarantee is offered or implied to the suitability of any underfloor heating system, installation and/or flooring products for any specific purpose.