Underfloor heating is nothing new. Indeed, it goes back at least 7,000 years when people used to cut trenches into the floors and cover them with stones which were heated from fires placed at strategic points within the building. However, things have come on apace since then, and today we have underfloor heating which can be either electric or a water-based system.

The electric underfloor heating uses heating wires or heating mats which have wires contained within them. These are very quick and easy to install, but more expensive to run than a water-based system. The latter uses heating pipes through which hot water is passed in order to produce the heat. The water can be heated by a boiler, by solar panels, or by a ground-source or air-source heat pump, and is simply pumped around the system. For larger rooms, a water-based system will be much cheaper to operate than an electric one, electricity being expensive and not likely to become any cheaper.

Whichever heating system is used, it will need to be covered using a screed, and there is no doubt that a modern liquid screed in Bristol will outperform the older sand and cement screed every time. It is cheaper to use underfloor heating with a liquid screed than with a sand and cement screed because the thermal conductivity of liquid gypsum screeds is nearly twice that of sand and cement.

Not only that, but a liquid gypsum screed can be laid considerably thinner than sand and cement, so it takes less time to heat up, and thus uses less energy to attain the required level of heat in the room.

Force Drying

Another very big advantage of liquid screeds is that they can be force dried, provided the right equipment is used and best practice observed. Liquid screed can be dry enough to walk on within 24 – 48 hours after laying, depending upon weather conditions. So, from that point of view there is a big benefit because any other contractors who need to work on the site are not unnecessarily delayed.

However, there is a big difference between the time that you can walk on a liquid screed and the point at which it is dry enough to install the final flooring surface. In fact, the drying time of a liquid screed with a depth of 50mm is said to be 60 days, at a rate of 1mm per day up to 40mm depth and ½mm per day for anything deeper. But this is based on an average temperature of 20°C and relative humidity of 60% through the whole of the drying time, and it is unlikely that this could be achieved in the UK for a constant period of two months. So, on a construction site, this will often extend to 90 days or even more.

Using force drying can bring the total drying and commissioning time down to just 28 days. The key to successful force drying is using the correct specialist drying equipment, total control of the environment (including temperature and humidity), and appropriate moisture testing. On any construction project, time is money, so being able to cut the drying time down to four weeks represents a considerable cost-saving.

Underfloor heating is often thought to be suitable only for high-end properties, and this is why architects will often opt for a radiator system in affordable housing. However, when underfloor heating is used in conjunction with a liquid screed and force drying, the overall cost savings can put it on a par with a radiator system. The benefits of underfloor heating will go on for as long as the building is in use.