Underfloor heating systems are being installed more and more in new build homes today as it has come to be realised that they provide several benefits over a radiator system. However, underfloor heating is nothing new: the Romans were using it 2,000 years ago by having trenches dug into floors and covering them with stone, heating from strategically placed fires.
Things have changed somewhat since those days, but the principle of underfloor heating remains the same. Today we have electricity, and that means that we can use it as a heat source. So the underfloor heating can be powered directly by electricity using either a heating cable or a heating mat which contains very fine heating cables.
Underfloor heating can also be provided using a pipe system which has warm water pumped through it. The heat source could be a boiler, or it could be a ground source or air source heat pump. The only electricity that is then needed is to run the pump to circulate the water.
At UK Screeds we install water-based underfloor heating systems because of the many advantages that they have over electricity. To begin with, they are much cheaper to run. Electricity tariffs are not cheap, and electric underfloor heating should not be used for large rooms for that reason. To be fair, water-based underfloor heating systems are more expensive to install and take a little longer, but once that is over, the cost benefits go on and on.
Whichever type of underfloor heating is installed, it will need to be covered with a screed, and as a flowing screed company in Surrey, we use liquid gypsum screed, also known as anhydrite screed.
This is far quicker to install than the traditional sand and cement screed because that has to be laid by a man working on his hands and knees using a trowel. It is also often mixed on it in a cement mixer which means that the batches can vary in consistency although on larger contracts it is often delivered ready mixed.
Our flowing liquid screed is delivered to site ready mixed and instead of getting down on our hands and knees all day, we simply connect a hose to a pump and switch the pump on. This delivers the screed into position very fast indeed – up to 20 times as fast as you can lay a sand and cement screed by hand. Time is money on any building contract, so the quicker you can lay the screed the better.
Because it is in liquid form it fully encloses the heating pipes leaving no gaps or voids as is almost certain to happen with a screed laid by hand. What this means is that the heat transfer into the room will be absolutely even across the room instead of having cold spots.
Another very big advantage of our flowing liquid screeds is that they will be dry enough for a man to walk on in 48 hours or even less, thus meaning that other contractors who need to work on the site are not going to suffer any delay.
Our liquid screed can also be laid more thinly than sand and cement. Typically, a sand and cement screed will need to be 75mm or more thick, when used in conjunction with underfloor heating. Contrast that with our liquid screed which only needs to be 45mm thick. Certainly, our liquid screed is more expensive than sand and cement, but we need less of it. When you add that to the speed of laying compared with a labourer with a trowel, the cost works out at around the same, for a much better product.
Although the speed of laying and drying is much quicker, the overall curing time of a screed is calculated at a rate of 1mm per day up to a depth of 40mm and 1mm every two days thereafter. So the overall drying time is less than sand and cement.
However, our liquid screed does not curl and doesn’t need any reinforcement. Additionally, shrinkage is very low, and large bays can be laid without fear of cracking. This means that our liquid screeds can be force dried, thus reducing the curing time even further before the final flooring can be fitted.