While most of our attention is zoned in on the types of flooring systems and products that designers specify, the subfloor that will lie underneath them requires an equal amount of consideration. Regardless of the type of flooring that you choose, subfloor prep and pre-installation considerations are needed.
Manufacturers are often blamed for flooring installations that fail, but many times these failures are caused by incorrect installation. Whether it’s a contractor taking a shortcut when pouring a slab or not ensuring that moisture within the subfloor is reduced, there are multiple things that are simply outside the control of flooring manufacturers.
Different sub-floors will require different characteristics to determine their suitability for floorcoverings. In some cases, a floor-covering can be placed directly on top a subfloor, but if the surface is rough or has other imperfections, additional preparations will be needed.
Your first step in the right direction is to consider everything that is involved in the entire flooring system. These behind the scene considerations include everything from screeds and underlays to underfloor heating and cooling and cable management. A holistic view of the complete installation will help contractors take a methodological approach to installing the floor.
The next step is to research the correct floor preparation techniques for some of the most common types of flooring:
Floor preparation for carpets
A concrete floor may be smooth and clean but not plane and level, or it may be too moist to accept floor coverings. An underlay should be used to create a smoother surface in this case. The substrate needs to be level, clean, dry and free of any contaminants before any type of underlayment or adhesive can be applied. In many cases, manufacturers will advise installers to unpack the carpet materials at least a day prior to installation so that they can acclimatise to room temperature.
Vinyl and resilient floorcoverings
While soft underlays are generally used for carpets and other textile materials, a harder underlay is often advised for vinyl and other resilient floorcoverings (check with the product manufacturer to determine the appropriate underlay for your specific product). The floor should be tested for moisture before vinyl flooring is installed and the moisture content shouldn’t exceed 3% before, during or after installation. A floor scraper can be used to ensure there are no high spots on the subfloor and that the surface is completely level. A belt sander or floor grinder may be necessary if the floor scraper isn’t able to remove all the high spots. After this has been done, the floor should be cleaned of dust and debris.
A good concrete floor/sub-floor is the result of sensible planning, careful design and detailing, adequate specifications, good workmanship and proper inspection. All resilient flooring materials require a smooth, hard, clean, level and even surface with not more than 3mm difference over 3 metres, not only for appearance but also for achieving a satisfactory adhesive bond and long-term durability. The floorcovering must be conditioned to the temperature of a floor for 1-2 days before installation.
Resilient flooring should be bridged or covered over expanding or contracting floor joints and seaming should be kept to a minimum. Seams should also be placed in areas exposed to the least amount of traffic.
Read the manufacturer’s guidelines as paint-on primers are often included in glue-down vinyl plank flooring products. Only use approved acrylic adhesives that are recommended by the flooring manufacturer.
Wood and laminate floorcoverings
The sub floor must be dry, level, firmly affixed and clean before wood or laminate flooring is installed. A suitable underlay can be used to compensate for unevenness, but unevenness should either be sanded down or levelled with a cement screed if the unevenness exceeds 2mm over a 2 metre length. It is important to examine the space between floors and doors, openings between rooms and corridor corners to ensure there is enough space (at least 1cm or 2cm floor boards stacked on top of each other), so that after laying the laminate floor, the doors can still be opened and closed over the bridging gap.
Being rigid materials, ceramic and porcelain tiles need a subfloor that can account for this without any fluctuation or movement. An uneven surface is never advisable but it is particularly important if ceramic tiles are being installed as tiles may crack or loosen.
All cracks and uneven patches in the concrete subfloor need to be repaired prior to installation. If there are large cracks, your only option may be to replace a large section of the slab. New concrete slabs should be left to cure for minimum 28 days before tiling. If you have a wooden subfloor, a cement backer board can be used to provide a solid, flat surface for tiles.
THINGS TO CONSIDER WHEN REMOVING OLD FLOORS
Use the following information about tools, equipment and removal methods before removing a floor:
Carpets and carpet tiles
Some tools that you may need during carpet and carpet tile removal include a carpet knife, hook knife, metal clamps, hammer, moulding bar, channel locks or pliers, floor scraper, broom and dustpan. In America and Europe, walk-behind or ride-on scrapers are commonly used to remove large areas of carpets, but this isn’t prevalent in South Africa. Hand tools are still being used to remove even large areas of carpet in local projects.
Resilient flooring – sheeting and tiles
Besides ride-on, walk-behind and push scrapers, hand tools such as a flat spade, hammer, pliers, a pry bar, utility knife, gloves, goggles and knee pads are often used in these projects. The removal of resilient flooring often leads to old adhesive residues that need to be ground off the screed before a new surface can be installed.
Specialised equipment is needed to remove adhesive from the floor after the cork has been removed. A scraper is generally used to lever up a corner of a cork tile, while mechanical floor scrapers are used for larger areas. A hammer and bolster or a heat gun can be used to remove stubborn batches of glue.
A putty knife, pliers, protective gloves, soapy water, adhesive removing solvents, a rag and respirator are needed to remove rubber tiles. The putty knife is used to detach the tile from the underlayment of the subfloor. When a portion of the tile is removed, it should be pulled-up carefully with a pair of pliers while loosening the leftover adhesive with the knife or grinding may be required if there is excessive residue.
Luxury Vinyl Tiles (LVTs)
A heat gun is used to soften the glue and a scraper is used to get underneath the tile or plan and lift it off the adhesive during removal.
Tools involved in removing wood flooring include hammers, chisels, leverage tools and scrapers. This job often requires brute force. For smaller areas, wood panels need to be removed or separated from the base floor with a crowbar, a claw hammer, a hand-sized sledge hammer and a cold chisel. For larger jobs, a circular saw can be used to cut seams into the wood panels to get access to the subflooring, but care must be taken because if the blade is sunk too far in it will start cutting the subflooring.
The same preparation and tools that is used for wood flooring removal is used for laminate flooring removal.
Ceramic and porcelain tiles
Ceramic and porcelain tiles are generally harder to remove than resilient flooring and it is a very labour intensive job. Most contractors still use the ‘hammer and chisel’ option although high quality machinery is available for this job.
Top Tips from contractors
• “Check the moisture content because you can’t do your preparation if your subfloor is moist,” – Brian Farrell from Mfarrel & Sons
• “It is very important that a subfloor is levelled when it is installed. Besides having a level subfloor, I cannot emphasise the importance of testing the moisture content enough,” – Pieter du Plessis from Florpro.
• “The first step in any flooring project should be investing in a thorough screed assessment,” – Alistair Mac Dougall from iTe Products.
• “Installers have a responsibility to educate themselves about the right installation conditions, products, techniques and tools to use,” – Jeffrey Africa from Tyl-Pro.
If you have a wood subfloor, a cement backer board can be used to provide a solid, flat surface for porcelain or ceramic tiles.
Full thanks and acknowledgement are given to www.belgotexfloors.co.za, www.builddirect.com, www.desso-businesscarpets.com, www.floorsdirect.co.za, https://www.florpro.co.za, www.homeguides.sfgate.com, www.iteproducts.co.za, http://www.mfarrellandsons.co.za, www.mkfloors.com.au and www.tylpro.co.za for the information contained in this article.