Common Problems When Laying Epoxy Floors (and How to Fix Them)

Diagnose and fix common epoxy flooring problems. From bubbling and peeling to colour issues – understand the causes and professional solutions.

Understanding Epoxy Floor Failures

Despite being one of the most durable flooring systems available, epoxy can fail if not properly installed. The good news is that most problems have identifiable causes and can be prevented with correct preparation and application techniques.

In our experience installing floors in demanding environments from airports to hospitals, we've seen every type of failure – and more importantly, learned how to prevent them.

Problem 1: Bubbling and Blistering

Bubbles in epoxy flooring are almost always caused by trapped air or moisture outgassing from the substrate. When epoxy cures, it generates heat, which can cause moisture in the concrete to vaporise and push up through the coating.

Prevention is better than cure. Always test moisture levels before coating using a plastic sheet test or moisture meter. If bubbles do appear during application, pop them immediately with a spike roller and re-roll the area.

Problem 2: Peeling and Delamination

Peeling occurs when the epoxy separates from the concrete surface. This is usually due to poor surface preparation – specifically, failing to remove contamination or create adequate surface profile.

Oil contamination is particularly problematic. Even invisible oil residue from vehicles or machinery prevents adhesion. In food-safe coatings for commercial kitchens, any cooking oil or grease must be completely removed before coating.

Fix: Remove the failed coating, grind the surface properly, degrease thoroughly, and recoat. There are no shortcuts.

Problem 3: Soft or Sticky Coating

If your epoxy remains tacky or soft weeks after application, you've got an incomplete cure. This is usually caused by incorrect mixing ratios, insufficient mixing, or applying in cold conditions below 10°C.

Less commonly, it can be due to contamination of one component before mixing. Always pour the hardener into the resin (not vice versa) and scrape the sides and bottom of the mixing container thoroughly.

Fix: If the coating is completely uncured, you'll need to remove it with a chemical stripper or grinder and start again. Partial curing can sometimes be salvaged by applying heat to accelerate the reaction.

Common Epoxy Floor Problems: Diagnostic Table

Problem 4: Discolouration and Yellowing

Standard epoxy can yellow over time when exposed to UV light. This is a cosmetic issue rather than a structural one, but it's unwanted in bright retail or showroom environments.

Prevention: Use aliphatic polyurethane topcoats for UV stability, especially in areas with natural light. For purely aesthetic spaces, consider polyaspartic systems which offer superior colour retention.

Problem 5: Visible Roller or Trowel Marks

Marks from application tools show when the epoxy starts to cure before you finish spreading it. This happens when you work too slowly or in temperatures that are too warm.

Fix: Work faster, use smaller batches in warm weather, and always maintain a wet edge. If marks do appear, light sanding between coats will level them out.

Problem 6: Poor Chemical Resistance

Some epoxy systems aren't suitable for aggressive chemical environments. If you're seeing etching, staining, or surface degradation in industrial areas, you may have specified the wrong system.

Different environments need different systems. Pharmaceutical and laboratory settings require specialist chemical-resistant formulations designed for acids, solvents, and aggressive cleaners.

Prevention Checklist

• Test moisture levels and don't coat if RH exceeds 75%
• Grind substrate to create CSP 2-3 profile minimum
• Remove all contamination – oil, grease, existing coatings
• Mix resin and hardener accurately and thoroughly
• Work within manufacturer's temperature and humidity guidelines
• Apply consistent thickness across the entire area
• Use spike roller to remove air bubbles during application
• Allow proper cure time between coats (don't rush)

When Problems Occur, Act Quickly

Small problems can become big problems if ignored. A few bubbles can spread, small areas of delamination can grow, and inadequate cure will never improve on its own.

The best approach is prevention through proper preparation and application. Our detailed guide on epoxy floor preparation walks through every stage of getting the substrate right.

If you're planning a project and want to understand the full installation process to avoid these pitfalls, start with our step-by-step laying guide which covers professional techniques from start to finish.