Tips for getting floor coating specifications right
Previously, floor coatings and finishing seemed to be a relatively straightforward product application. However, nowadays, because of the myriad of options and flooring materials available, it requires far more consideration. Everything from the thickness of the floor and the service environment to its performance characteristics, colour and surface finish properties are to be kept in mind when specifying floor coatings.
Floor coatings such as epoxy finishes are usually used on concrete floors where high traffic volume, clean and/or hygienic conditions and an aesthetic appearance are necessary. Some of the common applications include motor vehicle showrooms, pharmaceutical laboratories, food and beverage processing plants, general purpose warehouses, hospitals and large eventing venues.
Floor coatings applied over a sound and well-prepared substrate, when the blended epoxy components chemically react to create a product with strength, durability and aesthetic properties, are far more than only an aesthetic solution and are hard to match.
As with many flooring systems, it is much easier and more cost-effective to get the initial installation right than to try to “epoxy over epoxy” and repair a less-than-stellar job.
It is for this reason that FLOORS in Africa sought input from floor coating manufacturers to find out what some of their top tips are for specifying coatings. Here is what they say:
1. Poor substrate conditions
The look and performance of a floor covering is largely dependent on what lies below. Careful attention should therefore be paid to the correct preparation of the concrete substrate to ensure a successful and long-lasting installation.
“The substrate must be integrally sound, of significant strength, as well as smooth and level, as many coatings will suffer from surface imperfections or a poor aesthetic appearance if the floor below is not perfectly smooth and level,” comments TAL’s Technical Advice Supervisor, Sharon Margon.
Mark Griesel, Sika’s Regional Manager Coastal, concurs, “A minimum tensile strength of 1.5 MPa is required, and specification starts with the specified concrete mix design.”
2. Evaluate the surface
Chad Tosen, Soft Coverings Product Manager at Mapei, advises: “The surface must be suitable to accept the chosen floor coating, must be structurally sound, clean and free of any surface contamination. Check for cracks, density and porosity before installation. It is imperative that the surface be free of any moisture or the effects of hydrostatic or osmotic pressure. A DPC on the subgrade below the concrete plays a vital role in preventing rising moisture/damp.”
The type of surface preparation will also factor in the CSP guidelines, using equivalent mechanical surface preparation to achieve e.g., CSP-3, shot blasting as per ICRI guidelines.
3. Floor preparation
Our panel of experts all agree – it is of extreme importance to study the floor surface preparation required for each type of product considered. A floor is only as good as its substrate, so preparation before applying any coating is especially important.
For new floors, the concrete substrate must be fully cured and have attained the moisture content stipulated by the manufacturer of the floor covering. Excessive, or fluctuating moisture levels in the substrate or high moisture vapour emission rates will most certainly result in an installation failure, i.e. delamination from the substrate.
“If there is no damp-proof membrane below a surface bed or if moisture levels do not attain 50% Relative Humidity (RH)/3% moisture content, a suitable moisture or vapour barrier should be installed,” notes Sharon from TAL.
4. Importance of the correct specification
“Carefully consider the client’s requirements: for example wet, dry or warehousing conditions. The specific terms of test reports: for example slip-resistance (R-Classes), food compliance or biological resistance, or according to ISO 846 means specific installation requirements.
“This includes covering all the supply method statements with all aspects of the application, from A to Z, with the relevant system data sheets as well as a list of qualified specialised contractors for the application,” notes Mark from Sika.
Ensure that the proposed floor coating is fit for purpose, i.e. that the system and surface finish meet the client’s required service expectation and that no shortcuts have been taken in terms of product.
5. Application and environment
It is especially important to consider the usage of the floor before specifying a suitable epoxy system. If there is only going to be pedestrian traffic, a thin film coating will be sufficient. However, if there is going to be heavy-duty forklift and other mechanical traffic, a thicker, more durable coating or screed will need to be specified. The correct system and thickness are essential for longevity.
“With the application of a polyurethane coating, weather, moisture and contamination are of particular importance. The climate in KwaZulu-Natal for instance is more prone to moisture given the region’s humidity, and in winter places such as Bloemfontein, can reach temperatures well below freezing. Both climatic factors influence key application considerations as they could lead to flooring failures if not correctly addressed,” comments Peter Jones, National Sales Manager: Flooring at a.b.e. Construction Chemicals.
6. Maintenance plan
Specifying bodies also need to check that the contractor and client have included a suitable maintenance plan for the flooring system.
“Importantly, the supply method statement for a maintenance and cleaning regime must consider the nature of the industry, e.g. hygiene requirements, the size of the area to be cleaned and use of the correct chemicals for the types of contamination that need to be cleaned,” says Mark.
7. Suitable applicators
It is critical that a competent contractor be appointed to do the application. Not only do professional applicators have the correct equipment, they are also able to ensure that the required finish is achieved as specified.
“Installation of any floor coating needs to be effectively and carefully managed, hence the importance of working with an experienced installer of your chosen floor,” reiterates Chad from Mapei.
8. Client expectations
The client needs to understand the aesthetics and performance requirements of the product as well as cleaning and maintenance of the finished application. More importantly, the applicator must apply a sample of the product as a reference and standard that must be accepted by the client first.
“Criteria that must be considered when selecting a flooring system can vary considerably depending on the operational/service requirements. These criteria include slip resistance, abrasion resistance, chemical and acid resistance, thermal cycling and shock (where the ambient temperature of the environment changes significantly) hygiene (to meet HACCP requirements), as well as cleaning regimes,’ notes Sharon from TAL.
WHAT CAN GO WRONG? An epoxy or polyurethane resin floor can last for decades if it is specified and installed correctly. If this isn’t the case, one or more of the following problems may be the cause:
• Bubbling in floor coatings This is the most common problem with epoxy floors. The bubbles in cured epoxy floors are generally very small (the size of the pinhead) and may appear randomly or in clusters. These bubbles can be caused by outgassing of the concrete substrate or when the product isn’t mixed correctly or is mixed too fast, leading to air entrapment. Other sources of the problem can be excessive mixing such as using a power drill at high speed or when excessive temperature causes pressure differentials that lead to trapped air that wants to equalise. Slowly circulate the mixture in a large container and be sure to use the correct ratio when the resin and hardener are mixed.
• Craters and bubbles A bubble in an epoxy floor contains air or moisture, whereas a crater leaves an indentation in the surface that is generally caused through dirt or contamination while the epoxy is still curing.
• A dull and uneven appearance If the epoxy coat is applied in too hot or too cold climatic conditions, or when air flows over a curing surface, a dull and uneven appearance can be the result. Epoxy is very sensitive to temperature fluctuations and needs to be applied according to the manufacturer’s guidelines. Also, remove ventilation fans, switch off air-conditioning and close doors and large windows to prevent wind blowing across the curing surface. If dust is present during curing, it can cause small pinholes, or “fisheyes” in the final surface finish.
• Peeling Peeling and poor adhesion is usually the result of an inexperienced or careless applicator. It can also come from poor surface preparation, contaminated materials not being removed from the surface, incorrect mixing ratio of the resin and hardener, wide temperature variations or moisture trapped below the surface.
Specialised tip: Standard concrete generally has a compressive strength of only 25 MPa and requires a minimum of 1.5 MPa tensile adhesion strength. In most cases, this will not be sufficient to serve the environment that it will be subjected to, like damage from tools, equipment, shopping trolleys, forklifts, chemical resistance and aesthetics. This is why an epoxy flooring system is recommended.