Floor Screeding FAQs

Q1: What is the maximum thickness that screed can be laid?
A1: 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.

Q2: What is the minimum thickness that screed can be laid?
A2: 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.

Q3: When is it safe to walk on the screed once it has been laid?
A3: 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.

Q4: When can the final floor covering be applied to the screed?
A4: 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.

Q5: Can you put a heater in the building to dry the screed more quickly?
A5: 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.

Q6:  What are reinforced fibres used for?
A6: 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.

Q7: How many hours is the screed workable before it becomes unusable?
A7: Retarding / water reducing admixtures give optimum working times ranging from 8-12 hours. Weather conditions do, however, make these times vary.

Q8: How will the screed be delivered to site?
A8: 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.

Q9: How does the screed get transported to the working area?
A9: 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.

Q10: What actions do you carry out for curing the screed once it has been installed?
A10: 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.