When undertaking floor preparation in Marlow it is necessary to lay a screed over the substrate in order to ensure that the final floor surface is as flat and level as possible. While it is not a legal requirement to lay a screed, it is essential for the best possible finish of the flooring and is very necessary when installing underfloor heating in a new build because the heating pipes need to be covered.

At UK Screeds, we supply and install the latest anhydrite liquid screeds because of the many advantages that they have over and above a traditional sand and cement screed.

Not the least of these is the speed of laying the screed. When you lay a sand and cement screed it first has to be mixed on site in a cement mixer and then barrowed on to the substrate. It is then tipped out and levelled out by a worker using on hands and knees using a trowel. This is obviously a labour-intensive process. Furthermore, each barrow load of screed will not be totally consistent with the last one because the sand and cement is shovelled into the mixer and those amounts on each shovel will differ. This is why many larger sites now use ready-mixed sand and cement screed.

Once the screed has been levelled as much as possible, it then has to be left to dry fully before the final flooring can be laid. If underfloor heating is being installed, the screed needs to be 100mm thick or more as the screed is laid unbonded to the substrate and must be this deep if curling is to be avoided.

By contrast, our liquid screeds can be laid much thinner since they only need to be 25mm above the heating pipes and they do not curl. Drying times are calculated in the same way for both types of screeds and are at a rate of 1mm a day for the first 40mm and 1/2mm a day thereafter. So, a liquid screed of 50mm deep would dry in 60 days. The sand and cement screed would obviously take 100 days or more.

Force Drying

However, another advantage of liquid screeds is that they can be force dried using dehumidifiers, and in conjunction with the underfloor heating if it is installed, because they do not curl. This can bring the overall drying time of a liquid screed down to as little as four weeks which is a huge time saving compared with sand and cement.

Another advantage of liquid screeds is their thermal conductivity. This is almost twice that of sand and cement, with the result that less energy is used to bring the room up to temperature, and that means that there is a saving of electricity which will continue for the life of the building. It is also more environmentally friendly. In addition, because the screed is liquid it will full envelop the heating pipes which means that heat transfer into the room is even.

By contrast, when laying a sand and cement screed by hand it is very difficult to fully cover the heating pipes and there are almost always voids or gaps which means that the heat transfer will not be as even.