Screed preparation for vinyl flooring – What every contractor needs to know

by Ofentse Sefolo
Screed preparation for vinyl flooring – What every contractor needs to know

Vinyl flooring installations require a very specific preparation and installation technique. Here are seven recommendations for screed preparation that every flooring contractor should consider:

1. Remember that you are ultimately responsible to produce a quality screed
A screed needs to be smooth, level, at least 25MPa in strength, and free of cracks, dust, dirt and contaminants. Per the South Africa Standard Code of Practice 0155-1980 titled “Accuracy in Buildings”, the building contractor is ultimately responsible for the production of a Class 1 screed.

2. Conduct the “R2 coin test”
One of the requirements of a Class 1 screed is that the permissible deviation at any point under a 3m straight edge placed level in one direction is no greater than 3mm. We often recommend the “R2 coin test”: you shouldn’t be able to insert more than a R2 coin under the straight edge at any point along a 3m length on the screed.

3. Best practice to combat structural movement
Expansion and saw cut joints may have been specified. It is important to ensure that the correct expansion joint covers are used over all expansion joints. Saw cut joints should be cut about 40mm deep and need to be done with the floorplan and design in mind.

4. Reach out to product manufacturers if you are installing a screed in winter
Installation issues can occur when the temperature is 12ºC and below, which is why you should consult your adhesive and screed manufacturer to advise on best practice for their product if you are installing a screed during the winter months.

5. Mitigate moisture risks
Moisture issues lead to 80% of flooring installation failures. Moisture delaminates the screed and emulsifies the bond of the adhesive. With today’s new concrete formulations that often require a longer drying time, together with the fast-track building processes that generally do not allow for this additional time, most often, a reputable moisture barrier is recommended to manage this moisture risk. Don’t be fooled into thinking that moisture is only a problem in a new build. We increasingly come across instances in old buildings that are being refurbished and even screeds that have previously been fitted with tiles, carpets or vinyl sheeting.

6. Use the right tools to check moisture levels
Reputable probe method moisture reading instruments such as a Wagner meter or Protimeter will enable you to read the moisture levels at the correct depth, as testing surface moisture is simply not reliable enough. It is also vital to check readings in different areas of the building because factors such as ground conditions and ventilation can affect moisture readings differently.

7. Use a self-leveller
As it is very difficult to deliver a Class 1 screed, be sure to use a self-leveller. The substrate should be assessed to determine what thickness of self-leveller is required, but an average of at least 5mm is recommended.

For more information, visit www.polyflor.co.za, email marketing@polyflor.co.za or call +27 (11) 609 3500 to speak to Blythe or Wendy.

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