Frequently Asked Questions
The maximum recommended thickness for liquid flowing screed is 60mm. There is no maximum for traditional sand cement screed, however if the thickness is over 100mm it should be laid in two layers, each 50mm to be compacted.
The minimum recommended thickness for liquid flowing screed is 25mm bonded, 30mm unbonded and 40mm if floating. The minimum for traditional screeds is 40mm bonded, 50mm unbonded and 65mm floating. If requested, these minimums can be reduced further by the use of additives.
Liquid flowing screed can be accessed by foot after 24 hours. Traditional screeds can be accessed by foot after 48 hours, and full site traffic after 4 days. This can be reduced to allow foot traffic after only 12 hours, and site traffic within 24 hours with the use of specialist plasticisers and cements.
Liquid flowing screed dries at 1mm per day so the the drying times are determined by its thickness. Traditional screeds also dry at 1mm per day, however this can be reduced with the use of additives to reach targets of the screed being fully dry within 4-5 days, 10-12 days or 2mm per day. Exact drying times are dependent on temperature and the air flow within the building.
It is imperative not to force dry any screeds within the first 7 days of of being laid. Further advice can be provided upon request.
Polypropylene fibres are an average of 6mm in size and are used to achieve a more cohesive material and help control cracking. The fibres also replace the reinforced wire mesh.
Retarding / water reducing admixtures give optimum working times ranging from 8-12 hours. Weather conditions do, however, make these times vary.
Liquid flowing screeds are delivered to site in mixer trucks. Traditional screeds are delivered on a tipper and are tipped loose. Traditional screed can be delivered in bulk bags if requested.
Liquid flowing screed is poured out of wagons and into a screed pump. This is then pumped out of the pipe and into the working areas. Traditional screeds are moved with a wheelbarrow where there is sufficient access. Areas that have bad access or upper floor areas require a screed pump to be used. There is also the option of moving bulk bags with a pallet truck into working areas in shops or hospitals.
Screed needs to be protected from damage once laid. Adequate curing is essential and the screed should be covered with plastic sheeting for 7 days to ensure it retains moisture.