Underfloor heating: a real winter warmer

December 2014

Do you remember the wonderful feeling of waking up on Christmas morning when you were a kid?  Then you probably also remember the cold floor under your bare feet when running to see what presents Santa left under the tree. Fortunately, things have changed a lot since we were kids…
Yes, we may still get excited about Christmas. But now we can really enjoy the holiday season with our loved ones thanks to the underfloor heating (UFH) technology. Also referred to as radiant heating, UFH delivers a great feeling of soothing cosiness even in the coldest weather.

UFH: How Does It Work?
UFH systems work by turning the subfloor and floor finish into a huge radiator. Once the floor reaches the indoor air temperature, it emits heat evenly across the entire surface, warming up all the objects in the room and eliminating cold drafts. This way, you can enjoy an ideal indoor environment.
Regardless of whether you choose an electric (dry) or hydronic (wet) heating system, an essential element is the screed layer. Screeds can be used not only to get the right surface for the final floor, but also to improve the energy efficiency of UFH systems. For instance, a good-quality screed can retain and emit heat for longer if installed correctly.

Below are a few aspects to consider for great screed performance in underfloor heating.

Screeding options:

Three different types of screed are typically used with UFH systems:

1) traditional screeds – although appropriate for UFH, these screeds must be installed to a thickness of 75mm to prevent cracking and curling due to heat; with this depth of screed, the floor takes a long time to heat up and cool down, which makes the UFH system difficult to control;

2) free-flowing anhydrite screeds – these are calcium sulphate- or gypsum-based screeds blended with special aggregates and additives so that they can be installed at a reduced depth to facilitate heat transfer from the bottom up.

3) fast-drying screeds – characterised by excellent thermal conductivity and low thermal expansion, certain fast-drying screeds, such as FlexiDry products, deliver some of the best screeding options for UFH.

Thermal insulation can help improve the efficiency of the UFH system. First, thermal insulation applied between the concrete slab and heating elements prevents heat loss through the base. Second, the edges of the subfloor should be sealed all the way around to keep the heat inside the perimeter.

Most hydronic heating systems use plastic tubing. Since cementitious screeds do not adhere well to plastic, poor compaction around heating pipes has become a common problem in UFH. To avoid specific issues, such as inadequate soundness, cracking, and curling of screeds, good contractors should use stress alleviation measures, or polymer-modified screeds (e.g. FlexiDry products).
At HomeScreed, we not only offer customers high-quality UFH systems, but also help them get the right screed for their homes. By choosing us, you can rest assured that you will stay warm in the winter and celebrate Christmas in style year after year.

To find out what it takes to get a perfect screed for your floor, contact HomeScreed today or download our “Essential guide to the perfectly screeded floor“.
HomeScreed is a division on CSC Screeding Ltd