Given the dramatic pace of change in industries such as telecoms, information technology, the military and medical sectors, many people might consider the construction industry to be lagging behind in terms of innovation – but they would be wrong. Much has changed in the building sector it may be that these changes are just less visible or less publicised. The development of Liquid Floor Screed and Self Levelling Concrete are just a couple of small examples of the way in which the construction sector is moving forward.
What is Liquid Floor Screed?
Liquid screed is the modern alternative to conventional Sand and Cement screed. It is now widely used in the construction of domestic and commercial buildings and was developed to deliver a level and smooth surface onto which the chosen floor finish can be laid – tiles, wood, laminate etc. Liquid screed lends itself especially well for use with under floor heating.
Liquid screed goes under a number of other names such as; flowing screed, calcium sulphate screed or anhydrate screed. It has a multitude of beneficial features. A few of these are listed here;
- Can be walked on in 24-48 hours.
- Extremely low shrinkage and Minimal Thermal expansion (0.012mm/mK) so it offers minimal risk of cracking.
- Significantly reduced thickness when compared to traditional sand – cement screed. This means it can offer a significant weight saving as a result.
- Dries at a rate of 1mm per day up to a screed depth of 40mm and if necessary it can be force dried as early as 7 days after application.
- Protein free – cannot harbour harmful bacteria.
- Excellent thermal conductivity.
What is Self Levelling Concrete?
Self-levelling concrete is a modified form of cement that is highly liquid and flows easily. Unlike traditional concrete it does not require the addition of large volumes of water for placement.
Self-levelling concrete is typically used to create a flat, smooth surface with a compressive capability which is similar to or greater than that of traditional concrete.
With growing demand for flatter and smoother floors (often driven by flooring sector as floor coverings become thinner and floor tiles larger) quite understandably self-levelling concrete has become popular, as the degree of flatness and smoothness required from floors has increased.
When self-levelling concrete is poured, it has been described as flowing similar to pancake batter! A tool called a gauge rake is used to move it into place without spreading it too thin. The finishing is then done by lightly breaking the surface tension of the product using tools called Dappling Bars. The polymers in the self-levelling mix keep the viscosity of the concrete the same consistency from top to bottom so the sand aggregates do not sink to the bottom.
To ensure that the finished floor will be perfectly level a useful tool called a Tripod or Spider should be used.
What is a Screed Tripod?
A screed tripod is a simple but ingenious tool used to ensure a floor is laid exactly to the correct, desired level. The tripods are three legged devices with a central screw threaded shaft at the base of which is a circular disc. The disc can be raised or lowered to set the perfect required floor level (using a laser level) prior to the liquid screed – or the flowing concrete – being poured.
This is how we would advise on how best to use liquid screed tripods.
- Determine the desired level of the finished floor (prior to any floor finishing being applied i.e. tiles, laminate etc.) This level is known as the datum level. You will likely take your datum level from a fixed point such as the final finished floor level or a door sill. Place a Screed tripod next to this datum point and adjust the height of the tripod disc to exactly match the datum level – ideally you’d use a laser level for this.
- Leave this tripod in position and place additional tripods throughout the area to be screeded. We recommend a spacing of 1500mm between tripods.
- Set a laser level to the datum tripod disc and then transfer this level to all of the other tripod discs in turn, adjusting the height carefully until they are all set to your datum level.
Now it’s a case of simply pouring the screed – or flowing concrete.
Pour in the liquid screed up to the level of the tripod discs, ensure that there are no high or low areas of screed between each tripod. Once the screed has been poured remove all the tripods from site. Top Tip – don’t forget to clean each tripod carefully immediately after it has been removed to prevent any screed setting on the tripod. Pay special attention to the thread which should also be lubricated periodically to ensure a longer life.
- A fully stainless steel tripod will last much longer as it will be resistant to corrosion.
- Good height adjustment is important – our tripods will handle depths of between 10mm & 150mm.
- Stability is a key consideration – tripods falling over when the screed is poured in is hugely annoying. Metex tripods have thicker than average legs for extra stability, strength & durability.
If working at speed is important we have just introduced a threadless tripod which will dramatically reduce the set-up time. It also reduces the cleaning and maintenance time.
View details of the Fastpod here.
If you have any questions at all about liquid screed or flowing concrete and how to use screed tripods to level a floor please feel free to contact us. We’d be happy to hear from you.