Floor coating failures share a common thread: the system was chosen before the substrate and service conditions were properly understood. A thin-film epoxy applied over a damp slab will blister within months. A standard epoxy screed in a food processing facility will crack under thermal cycling. Getting the selection right means working through four variables in order: mechanical loading, chemical exposure, thermal shock, and surface preparation. Only then does product selection make sense.
The Four Variables That Drive System Selection
Mechanical Loading
Forklift traffic, pallet racking point loads and steel-wheeled trolleys all impose different stress profiles on a coating. Thin-film systems at 150 to 300 microns dry film thickness (DFT) can handle foot traffic and light wheeled loads, but they offer almost no impact resistance. Once you introduce hard-wheeled forklifts or drop impact from loading operations, you need a screed system at 2 to 9 mm thickness to distribute load across the slab rather than concentrating stress at the coating bond line.
Abrasion resistance is typically measured by Taber abraser testing. Epoxy screeds generally outperform polyurethane screeds on abrasion resistance under dry conditions. Where the floor is also wet or subject to thermal movement, the equation changes.
Chemical Exposure
Epoxy resists a wide range of dilute acids, alkalis and solvents, but it is not universal. Concentrated nitric acid, acetic acid above moderate concentrations, and some ketone solvents will attack standard epoxy resin systems. Polyurethane systems, particularly aromatic polyurethane screeds, offer better resistance to certain organic acids encountered in food processing, brewing and dairy operations.
Before specifying, obtain the manufacturer's chemical resistance table and cross-reference it against every chemical the floor will contact, including cleaning agents. Sodium hypochlorite at the concentrations used in food plant washdowns is aggressive enough to degrade some coating systems over time. Always check the datasheet, not the product name.
Thermal Shock
Epoxy is a relatively rigid material. Its coefficient of thermal expansion differs from concrete, and when a floor moves rapidly between temperatures, the bond line experiences shear stress. In cold stores where floors are hosed down with warm water, or in food processing areas where steam cleaning is routine, standard epoxy screeds can delaminate at the edges of drains and doorways where temperature differentials concentrate.
Polyurethane screeds are formulated with higher flexibility and better thermal shock resistance. Fosroc's polyurethane screed products, for example, are specifically positioned for food and beverage environments where thermal cycling is a design condition, not an occasional event. If your facility will see temperature swings greater than 30 degrees Celsius during normal operations, a polyurethane screed warrants serious consideration over epoxy.
Slip Resistance
AS 4586 classifies slip resistance for pedestrian surfaces. Wet areas in food processing, commercial kitchens and wet processing plants typically require a P4 or P5 rating under the pendulum test. Broadcast aggregate finishes, where quartz or aluminium oxide is seeded into the wet topcoat, are the standard method for achieving this. The aggregate size and broadcast rate determine the final classification. A smooth self-levelling epoxy finish may be appropriate in a dry warehouse but is unsuitable in any wet processing environment.
System Types and Where They Fit
Thin-Film Epoxy Seal Coats
Applied at 150 to 300 microns, these are penetrating or surface-applied systems that seal the slab surface against dusting and light chemical splash. They are appropriate for warehouses with foot traffic and light pallet jack use, plant rooms and areas where the primary requirement is dust suppression and ease of cleaning. They provide minimal mechanical protection and no meaningful resistance to impact or heavy wheeled loads. Cost per square metre is low, but so is the service life under anything beyond light duty.
Self-Levelling Epoxy Screeds
At 2 to 3 mm, self-levelling epoxy screeds are the workhorse of industrial flooring. They provide a smooth, chemically resistant surface suitable for manufacturing, logistics and general industrial use. They can be broadcast with aggregate for slip resistance or left smooth for areas requiring easy cleaning. Compressive strength of cured epoxy screeds typically exceeds 70 MPa, which is well above the slab substrate in most cases, meaning the bond to the substrate governs performance rather than the coating itself.
These systems are sensitive to moisture during application and to thermal shock in service. They are not the right choice for food processing areas with regular steam cleaning.
Heavy-Duty Polyurethane Screeds
Polyurethane screeds at 4 to 9 mm thickness are the standard specification for food and beverage processing, commercial kitchens, breweries and wet processing environments. The flexibility of the cured film accommodates thermal movement, and the chemistry of polyurethane provides better resistance to the organic acids and cleaning chemicals encountered in these industries.
Installation requires careful attention to joint detailing. Coved skirtings at the wall-floor junction are standard practice to eliminate the horizontal ledge where bacteria and cleaning chemicals accumulate. Drainage falls should be formed into the screed rather than relying on the slab fall alone, which requires coordination between the screed installer and the hydraulic design.
Anti-Static and ESD Systems
Electrostatic discharge (ESD) flooring is specified in electronics manufacturing, server rooms, munitions handling and some chemical processing environments where static ignition is a risk. These systems incorporate conductive carbon or metallic elements into the coating matrix, and they require a continuous copper earthing grid bonded to the building earth. The floor resistance target is typically between 10^6 and 10^9 ohms under AS/NZS 1020 or IEC 61340 depending on the application.
Anti-static flooring is a specialist specification. The earthing design should be confirmed by a qualified electrical engineer before the coating system is finalised.
Surface Preparation: Where Most Failures Start
No coating system performs beyond the quality of its bond to the substrate. Surface preparation is not a preliminary step; it is the most consequential part of the entire process.
Diamond Grinding vs Shot Blasting
Diamond grinding uses rotating diamond-tipped heads to remove laitance, surface contamination and weak surface layers. It produces a surface profile in the range of CSP 2 to CSP 4 under the ICRI Technical Guideline 310.2R scale. It is appropriate for slabs where the surface is generally sound and the primary goal is removing laitance and opening the pore structure for bonding.
Shot blasting propels steel shot at the surface under controlled conditions, producing a more aggressive profile in the range of CSP 4 to CSP 7. It is better suited to slabs with surface contamination from oils or curing compounds, or where a thicker screed system requires a more aggressive mechanical key. Shot blasting also reveals surface defects, honeycombing and delaminations that grinding can miss.
The required profile should be specified before work commences, not left to the applicator's judgement. Fosroc's application guidelines for their floor coating systems specify minimum surface profiles, and those figures should be used as the benchmark for substrate acceptance.
Moisture Testing
Moisture is the single most common cause of coating delamination and blistering. Water vapour migrating through a concrete slab creates osmotic pressure beneath an impermeable coating film. At sufficient pressure, the bond fails and the coating lifts.
Moisture testing should be conducted using the in-situ relative humidity probe method per AS 1884 or ASTM F2170, not the surface mat method, which underestimates moisture in slabs without a vapour barrier. Most epoxy coating manufacturers specify a maximum in-slab relative humidity of 75 to 80 per cent before application. Polyurethane systems may tolerate slightly higher readings, but the datasheet figure governs.
Testing should be completed at least 72 hours before scheduled application, with probes installed at one third of the slab depth. If readings exceed the specified limit, application must be deferred or a moisture-tolerant primer system used. Do not proceed on the assumption the slab will dry down in time.
The Vapour Barrier Problem
Slabs poured without a sub-slab vapour barrier will transmit ground moisture indefinitely, regardless of how long they cure. A slab that tests within acceptable limits during dry conditions may exceed limits after rainfall raises the water table. If the slab has no vapour barrier and is on ground, this risk must be factored into system selection. Moisture-tolerant epoxy primers can extend the acceptable humidity range, but they are not a substitute for a vapour barrier and they have limits. Where ground moisture is persistent, the coating specification should be reviewed by a flooring engineer before proceeding.
Putting It Together
A practical selection sequence looks like this. First, define the service conditions: traffic type and intensity, chemicals present, temperature range, and wet or dry environment. Second, assess the slab: age, whether a vapour barrier was installed, surface condition, and current moisture readings. Third, select the coating system that satisfies the service conditions and is compatible with the slab condition. Fourth, specify the surface preparation profile and acceptance criteria before the applicator mobilises.
Skipping any of these steps transfers the cost of failure to the remediation budget, which is always larger than the cost of getting the specification right the first time.
CSA supplies the Fosroc industrial floor coating range, covering thin-film epoxy systems, self-levelling screeds and polyurethane screed products for wet and food processing environments. Datasheets, coverage rates and technical data are available at constructionsupplies.group/au. For project quantities or product selection support, contact the trade desk directly.