CPD 2012 Module 9: Vinyl floor tiles in education projects

Vinyl floor tiles are manufactured from a number of layers of PVC, plasticisers and stabilisers, which together create a highly durable flooring surface. This presents an alternative to carpet, sheet vinyl and laminate flooring products, as well as natural flooring materials. Vinyl floor tiles are particularly suitable for use on education projects because they are less expensive than popular natural materials such as stone and wood, but can be designed to replicate their appearance.

Manufacture of vinyl floor tiles

The components of Karndean Designflooring’s Luxury Vinyl Tiles product are as follows:

• Base layer Designed to bond with adhesive and adhere to the subfloor.
• Middle layer The core of the tile, providing strength and stability.
• Photographic film The image that you actually see, a photograph of a natural product.
• Wear layer A hard-wearing but transparent layer embossed with a texture for grip and to enhance the visual effect. The thickness of this layer determines the performance of the floor. Generally, a rougher wear layer will increase the slip resistance.
• Polyurethane coating A thin coating applied during manufacture that seals the product and adds durability. This means there is no need to seal the product after installation, saving time and money.
• The raw materials of vinyl floor tiles are as follows:
• Plasticisers To make the material more flexible.
• Stabilisers To prevent the material from degrading.
• Fillers To bulk out the backing and middle layers to provide rigidity.
• Salt The main ingredient of PVC.
• Recycled plastic (PVC) Closed-loop recycling means that any manufacturing waste goes back into the system.
• Photographic film Onto which the design is printed to give the product a realistic appearance.
• Polyurethane coating Applied and fixed using ultraviolet light to keep the product in good condition and help prevent scratching.

To create each layer, PVC, plasticisers and stabilisers are blended together in an industrial mixer. This molten material is then exposed to heat and pressure and passed through a series of rollers to produce flat sheets of material. This is a process known as “calendering”.

The sheets are then laminated together to produce one sheet. During this process, the surface texture is applied to the top layer, using specially manufactured cylinders with metal plates to emboss the pattern onto the sheet.

The sheet then undergoes “annealing”, which removes internal stresses through controlled heating and cooling. This ensures the product is dimensionally stable. The product is then cut into tiles, strips or designs and packaged for sale.

Installation of vinyl floor tiles

Before installing vinyl floor tiles, it is important to prepare the sub-floor to ensure that the surface is dry and even. Karndean Designflooring recommends that its products are only laid on sub-floors where the moisture content level does not exceed 75%RH when tested with a hygrometer in accordance with BS8203-4:2001 (Installation of Resilient Floor Coverings). Where readings above 75%RH are recorded, it would be necessary to install a surface damp-proof membrane (DPM).

For readings below 75%RH, the next step depends on the sub-flooring material:

• New concrete floors should be cleaned and dried to remove any contamination — such as paint or plaster — before priming with neoprene or PVA primer.
• Power-floated concrete floors require abrasion, either by scarification or light shot blasting.
• Existing coverings, such as quarry tiles, mosaic, terrazzo or ceramics, should be degreased and abraded.
• Asphalt should be degreased, then primed with neat neoprene or epoxy primer.

When dry, the next step for all these surfaces is to apply a 3mm-minimum layer of smoothing underlayment.

Timber requires a different treatment. For example, tongue and groove floorboards should be well secured and any loose, worn or broken boards replaced. Any undulations should then
be filled with a suitable smoothing compound before overlaying with 6mm ply fastened at 150mm centres and a feathered finish applied. Individual manufacturers should offer specific advice about how to deal with other variants, such as chipboard, MDF, plywood and laminate floor coverings.

Another important step is to ensure correct acclimatisation of the vinyl flooring before installation. Karndean Designflooring recommends removing the tiles from their packaging and allowing them to condition (on location) at a constant temperature of 18-26ºC for 24 hours prior to installation. Ideally, this temperature should also be maintained during installation and for 24 hours afterwards.

Safety

The Building Regulations Part M requires that floors are “slip resistant”, and flooring in education environments requires a particularly high slip-resistance rating to deal with the hustle
and bustle of school life. There are two common methods of slip testing — ramp testing and pendulum testing:

Pendulum testing

This is the method of testing preferred by the Health & Safety Executive for the assessment of floor slipperiness in dry and contaminated conditions. The test uses a mechanical simulator to recreate the action of a person slipping. The imitation heel replicates a standard rubber shoe sole and, when swung across the test surface, gives a measurable skid distance. This then converted into a Pendulum Test Value (PTV). The following table shows how a PTV relates to the chance of slipping:

Ramp testing

This test is widely accepted in Continental Europe and the UK. It uses human test participants to demonstrate slip potential. The flooring is secured to a hinged ramp, which is raised slowly through 29 degrees until the participant slips off. A rating is awarded according to the angle reached before the tester slipped. Ratings range from R9 to R13. R9, the first rating, means the subject slipped when the ramp was between six and 10 degrees, while R13, the highest, means the ramp reached 35 degrees with no slippage at all.

In the US, the ramp test is called the “friction test” and in Europe it is known as DIN 51130 or the “DIN test”. For a comprehensive indication of how non-slip a material is, the test is conducted when the flooring is both dry and wet.

Maintenance

Vinyl tiles offer many maintenance advantages over traditional floors. The polyurethane layer can be cleaned with 100% biodegradable surfactants. Proprietary protection systems can provide barriers against scuff marks and fine scratches.