Underfloor heating: The basics
Find the best system for your project and discover what it will cost to install
Discover the best system for your project and learn how much it will cost to install it with this beginner’s guide
Water-based underfloor heating (UFH) is the preferred choice for many self builders and renovators . This is a hidden heating system, layered into the floor structure, so it reduces the need for wall-hogging radiators. That makes furniture placement easier and lends a sense of extra space, delivering the clean lines and open flow most homeowners want.
UFH’S low flow temperatures also marry up perfectly with renewable energy sources, such as heat pumps, delivering an efficiency uplift of up to 25%. Standard boilers also achieve a 5% performance boost with UFH compared to radiators, helping to ensure lower energy bills in use. A home heated this way simply feels cosier, too, providing gentle all-over warmth, without the hot and cold spots you get with radiators.
How does UFH work?
Water-based underfloor heating is designed to transform your chosen floor covering into a giant, low-temperature emitter. Fundamentally, UFH works by pumping a controlled flow of warm water through tubing embedded in the floor. In turn, this heats the floor covering and then the internal spaces to the temperature you’ve set on your room thermostat.
UFH is generally set to a backstop temperature of around 16ºc when it’s not required (such as overnight and while you’re out of the house). This provides better response times than switching the setup off completely, as it takes less energy to raise the temperature of the pre-warmed water to the desired level. If you wish, you can combine UFH with traditional emitters in some zones (for instance, most suppliers recommend a towel rail in bathrooms to provide a quick boost of heat when required).
Specifying your setup
To design the right system for your project, your supplier or heating engineer will need to know the planned performance of the house and the rooms the UFH is going into, along with full details of the floor build-up. This will allow them to calculate the required output and identify the best fixings to clip the pipes in place. System capacity is principally controlled by the pipe spacing and flow rate – so the design will look to optimise both to give you the most efficient results.
The pipework is usually laid in screed – a top layer of material that provides a smooth, flat base for your chosen flooring. This could be traditional sand-and-cement or a modern self-levelling liquid screed (for more on this, see the box overleaf). On a new home project, a typical build-up (from bottom to top) might be: floor structure (eg concrete or beam