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Low Profile Overlay UFH Systems – What to Consider

Low Profile Underfloor UFH Systems

Low Profile Overlay UFH Systems

Low profile overlay UFH systems have stormed the UK Underfloor heating market, proving popular with builders and renovators alike. The minimal floor height increase and the lack associated disruption is a ‘renovators dream’. Overlooking important factors could result in poor performance, efficiency and control. Installers must be aware of certain characteristics of low profile overlay UFH systems.

BS-EN 1264 does not determine system outputs in relation to low section systems with no insulation. The information available relating to the output of a low profile UFH system is currently from limited manufacturer information and some thermodynamic modelling.

Manifold Positioning

Manifold locations need careful consideration, shorter pipe loops restrict the total square meterage heated by each manifold when compared to a traditional 16mm system. Equally, pipe traffic running to and from the manifold will take up space.

Although an aesthetic decision may be to locate manifolds side by side, you should consider separating the locations. This reduces pipe concentration and potential overheating within the floor.

Sub Floor Preparation

Overlay floors often have a good load capacity, however, they are intended as the name suggests, an overlay solution. This type of system can not be used to span joists or battens. They must be installed on a structural floor.

Position the overlay panels once you have cleaned, levelled and in some cases primed the subfloor. It is easier and more cost-effective to address any levelling issues in the first instance. Working around imperfections or relying on the latex to hide any imperfections can be problematic and costly.

Preparation of Latex Finish

Certain floor types require a primer to seal to the latex particularly when tiling. Failure to do so may result in the tile adhesive de-bonding with the latex. The floor should also apply should you be using any other floor finish that requires a bonding agent.

For a wooden floor finish or a carpet, generally, the floor will only require priming as a protective measure. With a wide range of floor finished, levelling compounds and adhesives are available. You should always check compatibility and follow instructions carefully.

Standards and Building Regulations

There was a series of consultations between BEAMA Underfloor and Building Control regarding panel based Underfloor Heating Systems. After careful consideration, the two governing bodies confirmed that this type of overlay underfloor heating system does not require the provision of floor insulation to meet building regulations where it is not practicable to do so.
It is extremely important to consider thermal transfer through the floor finish, downward loss and the heating requirement of the room. Consider these aspects of the intention is to adequately heat the room rather than provide floor warming.

When installing an overlay underfloor heating system in a new build application, insulation values of the ground floor must provide a minimum U value of 0.2W/(m2k). Building Regulations Part L1a (2013) detail this further. You must also consider the minimum insulation levels, as set out in BS EN 1264-4.

Where practicable, you must adhere to these regulations and standards, although, BEAMA and Building Control note that the floor depth is the principal benefit of these systems and that this may preclude or limit the use of floor insulation.

Heat Outputs for Low Profile Overlay UFH Systems

At present, the calculation methods for determining heat outputs in relation to low section systems with no insulation. As such the information available in the marketplace is a result of thermal dynamic modelling and some, limited, testing by manufacturers.

Tailored Heat offers a design and supply of Low Profile Overlay Underfloor Heating Systems. Send your project details to info@tailoredheat.co.uk or contact us on 01228 210444