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Do you have to grind concrete before epoxy can be installed?

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Epoxy flooring
Policrete Team
Policrete Team
April 26, 2023
minute read

Why grinding concrete is essential for lasting epoxy floors

Is grinding your concrete floor really that important if you’re going to cover it in epoxy anyway? That’s actually a fair question. It’s only natural that concrete floors need some level of preparation before epoxy can be poured over them, but for inexperienced DIYers, ‘preparation’ usually means a sweep and a mop for a clean surface. Maybe, if they’ve got the time, a go-over or two with some medium-grit sandpaper will smooth out the concrete surface.

Here’s the absolute truth: if you want long-lasting epoxy flooring, then concrete grinding is absolutely necessary. There’s simply no way around it. We’re going to explain why — most importantly, we’re going to explain why getting a professional is the best way to go about it.

Policrete is Melbourne’s first and leading full-service concrete specialist. If you’re after durable, hygienic and long-lasting epoxy flooring for your home or business, we’re always ready to help.

3 reasons concrete grinding is critical for epoxy flooring

1. It restores the structural integrity of concrete surfaces

If you’ve had a concrete floor for practically any time, it’s almost certainly taken some damage. Concrete garage floors at homes and businesses (like panel beating garages, for example) are constantly compressed by the high vehicle traffic they endure. Indoor and outdoor polished concrete floors in low-moderate traffic areas may seem perfectly fine, but if the concrete was exposed to excess moisture (from rain or even mist) when it was first laid, it’s likely to be far more brittle than you expect.

The only way to tell how sound your existing floors are is to have them tested by a concrete specialist. If there’s any issue, grinding will likely be part of the solution. For significant issues, concrete grinding razes the floor surface back to the substrate, allowing fresh concrete to be laid if necessary.

2. Grinding creates level, flat and blemish-free floors

If level and flat mean the same thing to you, then chances are you’re thinking of the definition of level. 

  • A level floor is one that is parallel to the horizon.
  • A flat floor is one with no bumps, dips or warps in it. An inclined floor can be flat, though it is not level.

Before installing an epoxy floor coating, the underlying concrete must be both level and flat. If it is not, the wet epoxy resin will pool into the dips and crevices (meaning we’ll have to use more than is necessary) and lay extremely thin over the bumps and high points (meaning the epoxy won’t be as durable.)

It’s for these reasons you must also remove blemishes like chips, scrapes, cracks and crumbling spots in your concrete floor. Though smaller imperfections may not seem like a big deal now, the epoxy installation process — and time — will likely force those now-negligible cracks to worsen and eventually ruin your floors.

[feature_link]Read more: Keen to learn more? Here’s everything you need to know about how to install epoxy flooring.[/feature_link]

3. Give your concrete ‘teeth’ for the epoxy coating

If the idea is to prepare concrete for epoxy, it’s important to use a course concrete grinder to create a rough surface. This roughness isn’t akin to cracks or flaws in the concrete — it creates ‘teeth’ that are necessary for the wet epoxy resin to adhere to properly. The epoxy will then dry firmly, and be less likely to shift and warp over the concrete’s surface over time.

How concrete grinding gets done

As far as concrete preparation for epoxy coatings goes, concrete grinding is one of the less labour-intensive services. Putting aside the concrete assessment we may need to do and any other preparation procedures we may need to undertake, grinding concrete can be done relatively quickly and affordably.

But don’t let us make it sound easy — concrete grinding requires not only specialist knowledge, but specialist equipment. Neither is a given if you’re relying on a less-experienced business or just an enthusiastic DIYer.

What’s the alternative to grinding?

Every project requires a unique solution; your home’s garage floor can’t be prepared the same way as an industrial site’s production floor. Depending on your site, we may recommend acid etching or wet grinding as alternative preparations.

  • Wet grinding sees us flood the area with a shallow layer of water. The liquid instantly captures the dust created by the grinding preventing it from kicking up into the air and damaging the surrounding area or harming anyone through inhalation. We can then quickly clean away the wet slurry.
  • Acid etching sees us spreading a layer of industrial acid over the concrete, sizzling away any imperfections to achieve the same effect as a grind.

Both methods have their advantages and relevance, and we’ll always advise you on which method will work best for your site.

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