One of the most important factors in any construction project is the flooring. Of course, walls and the roof are important too, but the floor needs to take a lot of weight and it also needs to be as flat as possible.
Even in a private home there is quite a lot of weight – furniture, bookcases, beds, tables, baths, showers, cookers, fridges, freezers, and more. It has to be as flat as possible in order to lay the final floor surface – tiling, hardwood, carpet, laminate, vinyl, and so on. This is particularly important in the case of something such as tiles, because if the substrate is not flat and you glue the tiles directly on to it, then they will start to crack when people walk on it.
This is one of the reasons why it is essential to lay a screed on the substrate before adding the final floor surface. And, of course, the screed itself needs to be as flat and level as possible as well.
Traditional screed is composed simply of sand and cement and is then laid on the concrete substrate and levelled out as much as possible by a worker using a trowel. However, since this is done by hand with a worker on his knees, it can be very tiring. Not only that but achieving the optimum level of surface flatness with a traditional screed is almost impossible.
Surface Reqularity
The level of a screed is measured in terms of SR1, SR2, and SR3 – Surface Regularity 1, 2, or 3 – as defined by British Standards. SR1 is the best and is measured using a 2-metre straightedge on the surface. SR1 means that there must be no deviation of more than 3mm over the 2-metre length. SR2 allows for 5mm, and SR3 allows for up to 10mm.
With a sand and cement screed, it is usually no better than SR3. However, with one of the latest liquid screeds that we can provide at Top Mix, it will achieve at least SR2 and usually SR1. This is a far better surface upon which to lay the final flooring.
Our liquid screed is delivered to site and poured into position. It then just needs to be smoothed with a dappling bar in order to remove any air bubbles and can then be left to cure. Our liquid screed will be ready to walk on withing 24 – 48 hours. It does need sanding, but after that the final flooring can be laid.
There are many other benefits to liquid screed, especially when installing underfloor heating, but we will discuss those in another article.