If you find the screeding terms and terminologies all too confusing, please find our jargon buster below:
Walk on Time
Walk on time is the period of time after which light foot traffic can proceed on a freshly screeded surface. The general walk on time for most screeds is stipulated as 24- 48 hours. But for modified screeds such as FlexiDry it is as low as 12 hours.
Light Foot Traffic
Light foot traffic implies the movement of people on the screeded area with special care to avoid unnecessary impact or friction on the screeded surface. The earliest that light foot traffic can proceed is 12 hours for some modified screeds and 24-48 hours for traditional screeds.
General Site Traffic
General site traffic includes the normal activities that can be resumed on a newly screeded surface. A minimum of 5 – 7 days is generally required before general site traffic can proceed on a newly screeded surface. Screed protection is required to remove the direct contact with the screed surface. However special care should still be taken before loading heavy weights. If in doubt consult a qualified structural engineer for advice.
Curing of the Screed
Curing of Screed is the process of laying polythene sheets over the screeded area to ensure the retention of moisture during the setting process and to stop the surface from drying out quickly, leading to curling and cracking of the screed.
Curing time is the time for which the polythene sheets should be maintained on the screeded surface. Curing time is generally specified as 7 days as polythene sheets are usually required to be maintained on the surface for a week, and then opened up to enable a good airflow to assist the drying process. Polythene curing can be avoided for certain specialist cementitious screeds as well as Calcium Sulphate (Gypsum) screeds.
Screed Drying Times
Screed Drying Time is the time required for a newly laid screed to be dry enough to take on the final floor covering (carpets, tiles, vinyl etc). This could range from a few hours to 45 days after installation for some modified screeds, and in excess of 110 days for traditional screeds.
The ideal method to ensure the screed has dried to the required level is to conduct a moisture test. It is extremely important to carry out the moisture test as premature installation of the final floor covering can adversely affect the quality of the entire flooring.
This is the time required for screeded surfaces to reach the maximum strength. Irrespective of the type of screed used, most screeded surfaces reach their maximum strength at 28 days.
For example, even a screed with a drying time of 7 days will gain its final strength only after 28 days of installation. There are some premium priced products that can reach higher strength gains sooner but again, the final strength is reached only after 28 days. It is ideal to wait until the screed has reached its final strength to resume major activity levels on the screeded surface.
Screed protection is the protection of newly laid screeds from impact, friction and rough use to prevent the deterioration of the quality of the screed and the final flooring. Screed protection includes various measures from the regulation of site traffic to the installation of screed protectors to obtain the best possible result from the screed.
The British Standards stipulate that screeds should be protected from direct traffic as soon as physically possible after installation and only removed at the point of applying the final finish. It is important to pay special attention to the amount of weights loaded on the screed and the level of compression of insulations installed under the screed.
It is generally observed that the maximum damage is caused by ‘mobile elevating working platforms’ (MEWPs) collapsing the insulation and causing the screed to follow. A qualified structural engineer should consider the loadings for the use of the building both before and after construction. Paying special attention to this quarter of the provided information can go a long way in helping you hand over the screed to the final finishing contractor in perfect condition and in achieving the best possible results.