Flowing Screed Guide

Preparation

The preparation for flowing screed is very important. This part should be done with extreme care because if there are any gaps in the area that the flowing screed is applied to, leakages can occur and even worse, if it gets underneath the insulation/DPM it will lift it all up and it will float on top of the surface. if this happens, the only solution is to clean up and re-do the whole thing, that’s if you still have the job. This is an expensive problem to have so it is vital that the preparation is done with care and checked thoroughly.

The preparation for the most part will not differ to traditional screed. The only one difference is that there should not be any gaps where the screed could leak from. This means that when installing the insulation, all the joints should be taped up. In addition, if there is a gap in the wall, make sure some kind of reinforcement is placed there as the pressure of the screed can result in a leakage. In essence, the aim is to make a water tight pool so that none of the flowing screed can leak or break any of the barriers if there isn’t a solid wall in place.

Once the area is prepared, before the screed is applied, you will need to scatter a few screed tripods which are used as indicators when the right thickness is achieved.

Application

Flowing screed can be applied in two ways:

  1. Using a liquid screed pump
  2. Hiring a mobile liquid pump

The actual application process is still the same for both. The screeder will carry the hose through which the screed is pumped and will walk around the area making sure that the right level is achieved in all parts of the plot being screeded. Once the whole area has been pumped, a dapple bar will be used to get out any air bubbles and to leave just a slightly more smoother finish.

Thickness

Flowing screed is most commonly applied at a thickness of 40mm to 55mm, however, it can be as low a 25mm if bonded.

Drying Time

Depending on the product being used, typically there shouldn’t be any foot traffic on the freshly laid screed for 24-48 hours. The drying rate will be similar to traditional screed and will dry at a rate of 1mm per day up until 40mm although the weather and temperature will also affect this. However, flowing screed can be forced dry. This should,only be done after the screed has had 7 days to cure. If the flow screed has been applied over an underfloor heating system, then the water pipes can be heated to a warm temperature of roughly between 25-50 degrees. Patience is important in the drying process so it is best advised not to over do it with the forced drying. In most cases only 7 days of forced heating will be required but this will depend on the weather and temperature.

Advantages

  • Flowing screed is becoming a very common practice. This is largely due to it being applied in liquid form instead of being semi-dry like traditional screed is. The result is that it can be applied at a rate of 500-1000m2 and with certain products a coverage of 2000m2 can be achieved in a single day. In comparison, traditional screed is usually applied at a rate of 100-150m2 a day. As you can see, the difference in application rate is huge.
  • Another advantages of flowing screed is that it works perfectly with underfloor heating systems. Although traditional screed can be used over underfloor heating systems, they can sometimes leave air gaps and therefore, affect the efficiency of the system. As flowing screed has a liquid consistency, it is able to wrap around the system without leaving any air gaps.