Preparing Your Liquid Screed Floor for the Final Floor Covering

What is your final floor finish?

If it’s underfloor heating for tiled floors or any other material that requires adhering to the screed’s surface you will need your EasyFlow screed sanding before priming with an epoxy primer.

Sanding is required to remove surface laitance and absorb primer. Early sanding of your floor will improve drying times by removing the laitance allowing moisture to escape quicker.

Sanding should be carried out using an orbital sanding machine with integrated vacuum. This should be fitted with a 60 grit sand paper or carborundum disc.

NB. Sanding is to remove laitance/surface contamination and create a surface key it is not to remove screed depth.

Underfloor Heating Commissioning

Your underfloor heating system must be commissioned prior to the application of any final floor finishes. This is to ensure that any remaining moisture deep in the screed is forced out and conditions the screed to thermal movement prior to the application of final floor coverings. This is essential in underfloor heating for wooden flooring, tiled flooring, or any other surface.

Guidelines state that the underfloor heating should be:

• Commissioned at ambient floor temperatures (approximately 18 degrees or lowest manifold temperature).

• This temperature should be maintained for 24 hours, then raised by up to 5 degrees per day thereafter until the optimum running temperature is reached (to a maximum of 50 degrees).

• This should then be maintained for 7 days prior to the temperature being reduced by 5 degrees per day back to the starting point.

• The system should then be turned off and allowed to cool for 48 hours prior to moisture testing.

• Heating should not be switched back on for 14 days after tiling, it can then be brought up to the operating temperature gradually.

Moisture Testing

Please refer to our post ‘Drying Liquid Screed (12/08/2014)’ for advice on screed drying times and assisted drying.

Before priming the screed should be tested for any remaining moisture using a digital hygrometer, carbide bomb or oven test. Your floor covering installer should carry out one of these tests before deciding to apply your floor finish.

Moisture levels should be below 75% relative humidity (RH) or 0.5% moisture before priming can take place.

Screed drying time- it is essential to ensure that the screed is fully dried out prior to application of final floor finishes.

Priming

EasyFlow liquid screed will require priming prior to application of floor coverings in order to seal the porous surface of the screed and to prevent moisture from adhesives or smoothing compounds leaching into the screed.

Primer also acts as a barrier between the screed and any cement based smoothing compound or adhesive that may be used. (Compatible gypsum based adhesives and smoothing compounds are also available.)

We recommend the use of primers that are either acrylic dispersion or water based epoxy.