When installing underfloor heating in a building, it is necessary to lay a screed on top of the heating pipes so that the final flooring can be laid on top of that. The screed does a number of jobs, and a liquid anhydrite screed is the preferred type of screed for a number of reasons. In times past, a traditional sand and cement screed would have been used, but today a liquid screed has several advantages.
Just to begin with, when laying and installing underfloor heating pipes the ideal is for them to be totally immersed in the screed with no gaps or air pockets. If there are air pockets or voids it means that the heat will not transfer into the room evenly.
When you lay a traditional sand and cement screed by hand, it can be very difficult, if not nigh impossible, to fully cover the heating pipes without leaving any gaps. A liquid screed, on the other hand, is pumped into position using a hose and a pump and will automatically fully cover the heating pipes because it is in liquid form. This means that there will perfectly even heat transfer.
Another big advantage of liquid anhydrite screed is that it does not have to be laid as thickly as sand and cement. What this means is that it does not take so long to heat up the screed itself, so the heating system uses less energy to bring the room temperature up to the same level. The result of that is that, of course, there is a saving on the energy bill.
In addition to that, the liquid anhydrite screeds that we use at UK Screeds have nearly double the heat transfer properties of sand and cement, so again there is a saving of energy.
To be fair, anhydrite screed is more expensive than old-fashioned sand and cement which costs around £15/m3, with another £5/m3 if delivered ready mixed. Liquid anhydrite screed costs about half as much again, but of course, since it can be laid more thinly than sand and cement you don’t need so much of it.
However, there is another very big advantage to liquid anhydrite screed and that is that it is far, far quicker to lay than sand and cement.
Sand and cement, even if delivered ready-mixed, has to be laid by a labourer on hands and knees using a trowel. That is by no means a quick process. If you hire liquid screed services in Oxford from us at UK Screeds, we deliver the screed ready mixed and then we install it using a long hose and a pump.
What that means is that it is far faster for us to lay a liquid screed than you can get sand and cement laid: indeed, it has been calculated that we are up to 20 times as fast. It follows that the labour cost of laying liquid screed is considerably less than the alternative, so there is a very big saving on that alone.
Another big advantage of our liquid anhydrite screeds is that they simply do not suffer from shrinkage in the same way as sand and cement do. That means that it requires far fewer expansion joints – only across some doorway thresholds.
In addition, our liquid screeds are effectively self-levelling and self-curing. They just need to go over with a dappling bar in order to remove any air bubbles. This means that we can achieve a much more level surface than sand and cement which normally aims to get to SR3 which allows for a 10mm variation over 2 metres. Our liquid screed, by comparison, will always achieve SR2 which allows for a variation of only 5mm, but normally will get to SR1 which has a 3mm variation allowed, and it doesn’t get any better than that.
There is another very important factor with our liquid screeds and that is that they are all right to walk on after only 48 hours and often a lot less. What that means is that there is no delay to other contractors who need to work on the site.
As you can see, the benefits of liquid screeds are many: call us for further information.