When an architect is designing a new building there are dozens of things that need to be taken into consideration, one of which is the flooring. What type of floor will be fitted and why? Wood? Tile? Stone? Laminate? Vinyl? Carpet?
The answers to these questions will depend largely on the purpose of the building. For instance, if you were building a warehouse which would have forklift trucks in use, you would probably opt for concrete or stone. If you were designing a home in the country, some of the flooring will probably be wood.
No matter what type of flooring is to be fitted, in almost all instances you would not attach it to the concrete substrate. The flooring needs to be fitted to a surface that is as flat and level as it can be, and this is why most buildings are designed to have a screed laid over the substrate which will provide that flat and level surface.
There are two main types of screeds in use today, one of which is a mix of sand and cement which is usually in a ratio of one part cement to three parts of sand. Traditionally, this screed would be mixed on site in a cement mixer, then barrowed on to the substrate and subsequently laid and levelled out by a worker using a trowel.
This has certain inherent disadvantages, not the least of which is that each load of screed will be somewhat different from the previous one since the sand and cement is shovelled into the mixer by hand. For this reason, many larger contracts today use a sand and cement screed which is delivered to site ready mixed.
Either way, the process of laying and levelling is the same. There are British Standards for measuring how level a surface is, and these are referred to as SR1, SR2, and SR3, SR standing for Surface Regularity. The measurement is carried out by laying a two-metre straightedge on the surface and measuring any gaps underneath it with a slip gauge.
SR1 allows for a maximum gap at any point of 3mm. SR2 increases this to 5mm, while SR3 allows for up to 10mm. SR1 is referred to as High Standard, SR2 is Normal Standard, and SR3 is Utility Standard.
Unfortunately, when levelling a screed by hand with a trowel it is very unlikely that anything higher than SR3 will be achieved.
Many new builds today also incorporate underfloor heating because of the advantages that is has over a radiator system. Underfloor heating can either be electric or it can be a water-based system which uses heated water which is pumped through pipes under the floor. The water can be heated by a boiler, solar power, or an air source or ground source heat pump.
Electricity Is Expensive
Unfortunately, electricity is expensive, and the price of it is only going one way, in part thanks to Vladimir Putin. This means that electric underfloor heating can be very expensive to run, especially in a large room. If you wanted to use it in a bathroom which only needs heating for a small amount of time, it might be practical, but for a living room a water-based system is far cheaper to run. Certainly, an electric system is less expensive to install than a water system, but the running costs will very quickly pay for the difference, and then there is an ongoing energy saving, and thus money saving, for the life of the building.
However, when you install a sand and cement screed by hand, another issue is fully covering the heating pipes in order to ensure an even distribution of heat into the room. This is almost impossible to achieve, and so there will be gaps or voids in places around the pipes.
All of this is why so many architects today are using a liquid screed instead of the older sand and cement. If you install a liquid screed in Bristol, also known as a flowing screed, the contractor will deliver it to site ready mixed. A pump and a long hose is then attached to the delivery truck and the screed is simply pumped into place. Because the screed is liquid it flows all over the heating pipes leaving no gaps.
You might use a flowing screed in Swindon and obviously the same thing applies. Not only that, but liquid screed is so much quicker to install – up to 20 times as fast as a man on hands and knees with a trowel.
Another benefit is that a liquid gypsum screed (gypsum is used in place of cement) has almost twice the thermal conductivity of sand and cement, and so less energy is required to heat the room to the required temperature. There are also other benefits such as the fact that liquid screed can be laid thinner than sand and cement because it does not curl.
