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Fast drying screed additive (formerly RonaScreed 8 Day Overlay)


RonaScreed FastDry Prompt is a fast-drying additive for site batched screeds used to quickly reduce the level of retained moisture within the screed. This allows floor coverings to be laid over the screed much sooner than with conventional screeds. RonaScreed FastDry Prompt gains strength quickly, permitting early access by following trades.


Drying of screeds incorporating RonaScreed FastDry Prompt is influenced by heat generated during curing, meaning drying of thicker screeds is faster per millimetre of screed thickness. Screeds installed at 50mm can accept moisture sensitive floor coverings after only 4 days, 75mm and 100mm screeds can accept the same coverings after only 6 days.

Time taken to achieve 75% RH at the surface of the screed
Screed Type50mm75mm100mm
RonaScreed FastDry Prompt (Mix 1 & 2)8 days9 days10 days
RonaScreed FastDry Prompt (Mix 3)4 days6 days6 days
Market competitor14 days21 daysNo data
Standard sand and cement50 days100 days175 days

The drying data is based on drying at 20°C and 65% relative humidity. Low temperature, high humidity, increased screed thickness, and changing the mix design will delay drying. If the screed is covered with a curing membrane such as polythene, then the drying time starts when the membrane is removed. The relative humidity (RH) at the surface of the screed should be measured with a hygrometer before proceeding to lay floor coverings. Standard practices should be followed.


The drying speed of RonaScreed FastDry Prompt means commissioning of underfloor heating systems, or use of dehumidifiers can commence after only 2 days at 75mm and 10mm thickness at 20°C and 60-65% air humidity.


RonaScreed FastDry Prompt screeds can be laid either bonded, unbonded, or floating, determined by the substrate type. Bonded screeds must be laid on to a suitably prepared substrate (concrete slabs or existing screed). Unbonded screeds are those laid on a separating layer or preformed damp proof membrane. Floating screeds are those laid on to an insulation board or acoustic layer.


RonaScreed FastDry Prompt is supplied in 20, 210, and 1000 litre units.

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