Using underfloor heating systems (UFH) is an effective way to keep your home warm as the heat rises from the base of the room and across the whole room rather than from single point radiators. It frees your walls from those radiators, giving your property a clean and minimalist look and allowing more choice on where to place furniture and appliances. It also feels great under your feet!

When installing UFH, you need to apply a floor screed to bury the pipework and enhance the overall efficiency. In effect, the floor becomes a huge flat concrete radiator. Most professionals recommend using self-levelling liquid floor screed as it can be applied quickly and gives a smooth and level floor covering.

What is liquid floor screed made of?

They can be either cement-based or anhydrite (aka gypsum, the main constituent of wall plasters) – based. A cement-based screed works in wet or dry environments and can be used under all types of flooring. It is easy to install and is usually ready to carry foot traffic the next or following day. Anhydrite-based floor screed is similarly easy to install and hardens quickly but is not recommended under wet rooms as should moisture ingress occur it will soften the screed and blow it like wall plaster after a flood. Also if using anhydrite-screeds note that the surface will have to be sanded and primed before applying tiles. Cement-based screeds need neither sanding nor priming and dry in 15 to 20 days as opposed to anhydrite-based which take about 60 days to dry.

Why is liquid screed ideal for Underfloor Heating Systems?

Liquid floor screed is a good long term investment, especially if you have an underfloor heating system. It encases the pipes entirely, eliminating air bubbles and maximising thermal conductivity, i.e. the speed at which the floor warms up after turning on the heating. Traditional sand/cement screeds work fine over UFH but the heat transfer will be slower as the product is less dense. Traditional sand/cement screed can be smooth and level but this depends on the skill of the crew applying it.

What should be the screed thickness with an Under Floor Heating System?

Floor screed is traditionally 50mm to 65mm thick, the former more likely for liquid screeds and the latter more likely for traditional screeds. When applying liquid screed over wet underfloor heating systems, the thickness is usually about 50mm. However, the important depth is the cover over the underfloor heating pipes which must be 25mm minimum. Aside from this, you need to put a polythene membrane on top of the insulation prior to clipping the underfloor heating pipes into place. This is to ensure that the screed does not allow heat to be transmitted downwards away from the room to be heated. Also under no circumstances allow exposed aluminium foil, which could be part of the insulation, to contact the floor screed as an adverse chemical reaction may cause blistering

If you are looking to have your property installed with liquid cement screed, our team at Longfloor can help you. We provide quality cement-based screed that is suitable for any project. For any enquiries, please ring us on 01629 540 284 or email us at and our team will be pleased to assist you. To view a video on liquid cement floor being installed go to