When laying the final flooring in a new build project it may seem a little trite to say that it needs to be as level and flat as it can possibly be, yet that is always the case. While there is no legal requirement to lay a screed on the substrate before fitting the final flooring, it is the way to go, whether or not you are installing underfloor heating.
If you are installing a water-based underfloor heating system, then it is essential that the pipes are encased in a screed before laying tile, timber, or anything else. There are several different types of screed available, and traditionally it has been the case that a mix of around one part of cement to three parts of sharp sand has been the norm. This can either be mixed on-site or in the case of larger sites may be delivered ready-mixed.
Mixing on site is very labour intensive and can obviously lead to inconsistency, as it relies on labourers shovelling sand and cement into a cement mixer. It is probably safe to say that no two batches are identical. Ready-mixed is obviously better from this point of view. It can have retardants added in order to delay the set so that it can be worked all day.
Whichever method is used, the sand and cement screed mix then has to be trowelled into position and levelled by a labourer, and this can take a considerable amount of time. This is one of the reasons why liquid anhydrite screeds such as the ones we install at UK Screeds have been gaining so much popularity over the last few years.
Our screeds are made using calcium sulphate in place of the cement and are also delivered to the site ready-mixed. One big difference is that they are in liquid form, and what we do is to connect a pump and a hose to the delivery truck and simply pump the liquid screed into position. As you can imagine, this is far quicker than trowelling a semi-solid mix into position by hand, and in fact, it is reckoned that it is about 20 times as fast. This makes for huge savings on labour costs when working on a project. We have been known to lay 100 square metres in 45 minutes and can easily lay the ground floor of a house in the morning.
Now because our screed is in liquid form it is what is known as self-levelling. If you think about it if you pour water into a glass, after a minute or so the top will become flat and level without needing to do anything to it. In fact, once the screed is poured, we do run over it with a dappling bar, but this is merely to remove any air bubbles.
You might also think that because the screed is liquid it will take a long time to dry, but the opposite is the case. Our screeds will be dry enough to take foot traffic in as little as 24 hours and certainly within 48. This is another big time-saver because it means that other contractors who need to work on the site are not unnecessarily delayed.
Of course, before laying the screed, floor preparation in Oxfordshire is crucial, and we work with our customers who want to undertake the floor preparation themselves if they simply want us to deliver and pour the screed.
However, in the case of underfloor heating installation, we can deal with everything in the way of preparation. The floor needs to be clean, with any debris removed, and then the insulation boards can be laid. This has to be done while ensuring that they are flat and level on the substrate. If any service pipes are in place, the insulation boards need to have grooves cut in order to accommodate them. Any vertical services need an edging strip attached before the tanking membrane is fitted. The underfloor heating pipes have to be fitted on top of the tanking membrane and it has to be done in such a way that the pipes will remain in place when the screed is poured.
You can rely on us to undertake the floor preparation with care and attention to detail, as it is critical that this is carried out to the very highest standard.