Liquid floor screeds are becoming more and more popular, and for a number of very good reasons. They are a highly versatile material and are especially beneficial when used in conjunction with underfloor heating because they make the system higher in thermal efficiency.
Just to begin with, they are far quicker and easier to lay than a traditional sand and cement screed. A sand and cement screed is very often mixed on site in a cement mixer, and this of itself leads to inconsistency in the mix. One batch will not be exactly the same as the last batch. This is why, on larger projects, the sand and cement screed is now delivered to site ready mixed,
However, whichever way the screed is mixed, the laying process is still the same, with a worker on hands and knees levelling it out and flattening it using a hand trowel. This takes a considerable amount of time, and when used in conjunction with underfloor heating it is almost impossible to get the heating pipes evenly covered with the screed. This means that there will be air pockets in the screed, and this leads to uneven heat transfer into the room above.
By contrast, a liquid screed is delivered to the site ready mixed and then a pump and hose are connected, and the screed is simply pumped into position on the subfloor. Because it is in liquid form, it levels itself out. Indeed, at UK Screeds, as liquid floor screed contractors in Reading, the only thing that we need to do after pumping the screed is to run over it in two directions with a dappling bar just to remove any air bubbles and then we can leave the screed alone to dry.
As Much As 2,000 Square Metres In A Day
Laying a liquid screed in this manner means that we can cover an area of as much as 2,000 square feet in a single day. This is up to 20 times as fast as a skilled worker can lay a traditional sand and cement screed. Now on any contract, time is money, and laying a liquid screed saves untold man hours. Although our liquid anhydrite screed costs more than sand and cement, by the time you take the cost savings of labour into account it brings them to about the same level.
Furthermore, our liquid screeds dry much faster. They will be dry enough to walk on in as little as 24 hours in warm weather, and no more than 48 hours in any sort of weather. What this means is that other contractors who need to work on the site do not get held up waiting for a screed to dry. Two days at the most, and they can get on with whatever they need to do.
Another very big benefit is that when used in conjunction with underfloor heating, the screed will totally envelop the heating pipes, for the simple reason that it is in liquid form. This means that there are no voids or air pockets that you get with a sand and cement screed, so the result is that you get a completely even transfer of heat into the room.
Twice The Thermal Conductivity
In addition to that, an anhydrite screed has almost twice the thermal conductivity of sand and cement. The result of that is that it takes less energy to achieve the same level of heat in the room.
Another benefit of liquid anhydrite screeds is that they do not curl, and shrinkage is at an absolute minimum. So, the screed is not going to crack, which can happen with a traditional screed.
Because the screed is liquid, it is also much easier to achieve maximum surface regularity. Surface Regularity, or SR, is measured as SR1, SR2, or SR3. SR1 means that when a straightedge of two metres is laid on the screed surface, there will be a maximum deviation between it and the screed of 3mm at any given point when measured with a slip gauge. SR2 allows for 5mm, and SR3 is 10mm.
At UK Screeds, we always achieve a minimum of SR2, and in most cases it will be SR1, and that is as good as it gets.