If you are having a liquid screed floor installed, the sub-floor area and any underfloor heating components need careful preparation. We advise that guidelines are carefully followed in order to achieve the best finished results.
Prior to the flowing screed being applied the building should be as weather tight as possible, with at least the roof in place and all missing glazing or door openings should be temporarily sealed using polythene, insulation or ply.
Where the flowing screed is to be applied floating over insulation, the boards should be installed flat to substrate and be free from excessive movement/rocking. The perimeter strip should be installed to all walls and uprights within the screed. The strip should be installed without over stretching and should be pushed fully into all corners.
The insulation should then be overlaid using minimum 500 gauge polythene overlapped by 100mm and taped. The polythene should be laid flat with minimal ridges.
Underfloor heating pipes should be installed to manufacturer’s spacing’s and guidelines, as a minimum the pipe should be secured using either a clip rail or staple every 400mm. The pipe should be well secured to prevent floating during the application of the flowing screed.
It is essential that the pipe work be pressure tested (preferably with water) prior to installation of screed, this is to ensure there are no leaks.
Finished preparation should be completely water tight to prevent leaking, polythene and other materials should be grease free and sitting flat to the insulation boards and all pipes and conduits running in the screed must be fully secured.
It is important to know that there is a chemical reaction if the gypsum based screed comes into contact with the aluminium backing on most insulation panels, Hydrogen is created which would cause air bubbles to appear on the surface of your screed. NEVER use aluminium tape to seal the joints in your membrane.
Where the floor ratio is greater than 1:6, in doorways for example, expansion joints are required – these need to sit snugly over the pipes, and must allow screed to flow evenly to each side. Fit control joints where needed.
BEFORE WE ARRIVE:
QUANTITIES & DISTANCES
For us to deliver an efficient service at competitive rates, we need to know a few key measurements:
Volume of screed: calculated from your floor area, we can help you determine the volume, allowing for depth, surface area, and underfloor heating systems.
The distance from the pumping vehicle to the farthest point of the pour.
The height of any vertical parts of the route.
With this information, we can better estimate the time it will take and the number of technicians needed to complete the pour.
It is vital you ensure that there is sufficient access to your site for a standard sized concrete mixer truck, and there is an appropriate hard level surface for it to stand on.
We also need:
A water supply and hosepipe.
Sufficient plastic sheeting to protect the area where the pipeline connects to the pump.
A vessel (skip, wheelbarrows, wash out bag etc.) or waste area for unused materials.
Space to clean our equipment
Immediately After Pouring
PLEASE NOTE : FACTORS TO BE considered with drying:
Room Temperature– Elevating the room temperature will assist the screed to dry through improved evaporation.
The area poured will be suitable for taking light foot traffic at 48 – 72 hours
Relative Humidity– It is important to provide good ventilation (dehumidification) to ensure a low RH is achieved as a high RH can slow the drying performance of the screed. Dehumidifiers can be used as early as 72 hours after the screed has been placed. The optimum moisture for the screed before laying floor coverings is below 75% RH (0.5% moisture).
Moisture Ingress– Flowing screed should be protected from moisture ingress to prevent rehydration which will delay the drying process.
Screed Temperature– UFH can be commissioned at 7 days, this raises the vapour pressure greatly improving the drying characteristics of the screed. This should be combined with ventilation (dehumidification). After 7 days, you can commission the under-floor heating on the lowest setting for the first 24 hours, then raise at a rate of 5 degrees per day to a maximum of 50 degrees, this must be a controlled increase of the temperature, so as not to allow the screed to suffer from thermal shock. The underfloor heating should be turned off for 48 hours prior to doing the moisture content testing.
(gyvlon) Anhydrayte Screed Drying Times:
The rate at which flowing screed dries can vary widely, depending on individual conditions. Standard rates for Anhydrite Screed are 1mm per day for the first 40mm, and then ½ mm per day for any further depth. So, a floor of 50mm would take 60 days to dry.
(longfloor) Cement based screed drying times:
Longfloor will be suitable to receive non-moisture sensitive floor finishes between 7-14 days. In ideal conditions (20°C and 65% relative humidity) the screed will have achieved 75% R/H (0.5% moisture) at 21 days. Underfloor heating systems can be turned on after 10 days and the system gradually brought up to operating temperature.
lume of screed: calculated from your floor area, we can help you determine the