Process Of Epoxy Flooring Surface Preparation:

grinding concrete for epoxy floor prep

After 10 Years On the Job, Here’s What I’ve Learned About Epoxy Floor Surface Prep

My name is Brandon and I’ve been installing and repairing floors for the last decade. In that time, I’ve performed all types of flooring services – flat work, concrete stain – you name it. But the one type of flooring I get asked about most these days is epoxy, and for good reason, they look pretty darn slick if you ask me.

But as great as epoxy floors can turn out, they’re definitely not a case of “slap it on and done.” Far from it. In my experience, the key to epoxy flooring success lies in the prep work. Do that right, and you’ll have a floor that was worth the investment. Cut corners or rush through it though, and you’ll wind up with cracks, peeling, and other big headaches down the road.

Step-by-Step Guide to surface preparation for epoxy flooring

Over the years, I’ve come up with a process for epoxy floor prep that works. It helps avoid the biggest pitfalls I see and sets up a solid foundation for the epoxy application.

Here’s an overview of my tried-and-true epoxy floor surface prep process in 6 key steps:

Step 1: Deep Clean the Concrete

The first thing I tell my crews whenever we’re doing an epoxy job is “clean that concrete within an inch of its life!” Grease, oil, mildew, paint splatters – it all has to go. Otherwise it can keep the epoxy from properly adhering, which causes peeling and other post-installation nightmares. 

We start by manually scraping off and sweeping away any big debris or loose material from the slab. Then we break out the mops, brushes, pressure washers and heavy duty concrete degreaser to really scour the surface. It’s hard work, but it makes all the difference.

Step 2: Repair Cracks and Holes  

Once the slab is squeaky clean, it’s time to patch any cracks or divots. Remember, epoxy is thick like syrup – it will conform to every imperfection in that slab. I do a careful floor inspection, identifying any sizeable spiderweb cracks wider than a couple pieces of paper stacked, or divots deeper than about a quarter inch or so. 

We thoroughly map out locations of fractures and damage. Then I fill any imperfections using specialized patching compounds and concrete epoxy fillers to properly repair problem areas and get the surface smoothed for an even finish.

No bumps or cracks means no popping off or peeling later on. If your concrete has low areas, now is the time to bring out some self leveler and get your surface smooth so your new epoxy meets the perfection you’re looking for. 

Step 3: Profile the Concrete Surface

Two Men Using Walk Behind Concrete Grinder

Now comes one of the most important parts of prep work for epoxies in my book: concrete profiling. This opens up the surface of the slab so the epoxy has something to grip onto. 

There are a few ways to accomplish this, but my go-to is diamond grinding. My crew goes over the whole slab with a walk-behind diamond grinder. It’s kind of like sanding wood, just way tougher. The diamonds roughen up and “tooth” the concrete surface to give the epoxy something to grab. You want to grind down to the aggregate by removing the smooth “Cream Layer” that forms on top of concrete while it’s setting up after the original pour.  

You can achieve a similar effect by using diamond grinding pads mounted on a floor buffer but it will take quite a bit more time as it removes less material per rotationAnother DIY option is Acid etching, it opens up pores and etches little grooves in the concrete surface that the epoxy seeps into, similar to the diamond grinding effect. This does not smooth out the surface like grinding would. 

Shot blasting is another option you’ll sometimes see the Pros use for concrete profiling. That can work too, especially in areas where minimizing dust is critical, it does take more time and in my experience diamond grinding gives consistent results. You can actually grind the floor wet if dust mitigation is absolutely necessary, but you must wet vac up the slurry as you go or the particles will settle back into the porous concrete and undue your work. 

For all the floor perimeter I use an angle grinder with a diamond cup wheel and dust trap attached to a shop vac.  You will want to put pressure on the front of the grinding wheel to ensure its leveling out high points in the concrete.

During this process strict PPE guidelines keep my crew safe when grinding. High-quality respirators and disposable suits are vital.

Step 4: Edge Work 

Once the slab itself is prepped, we shift focus to the perimeter edges. Any seam between the epoxy and wall base needs extra attention to prevent peeling or moisture seeping under the floor later on. 

There’s a few standard procedures we take care of in the edge work phase:

  • Grinding down high spots: We diamond grind down any part of the slab that slopes up higher than the rest within about 6 inches of a wall. That transition needs to be perfectly flush or moisture can get underneath and lift the epoxy over time. 
  • Installing foam backer rod: We force lengths of foam backer rod into any visible slab-wall seam all the way around the perimeter. This helps control the epoxy thickness near the edges.
  • Caulking concrete-wall joints: Next we seal over the backer rod with a flexible polyurea caulk. This waterproofs that vulnerable seam so moisture can’t undermine the epoxy bond.  
  • Creating perimeter keys: Finally, we use a concrete saw to cut 1⁄4 inch deep keys along the slab perimeter, about 6 inches from the wall. As we pour the epoxy, this trench creates a solid mechanical lock on the outer edges. This is especially useful where your garage floor meets the driveway. We want the epoxy to have a small channel at the transition so it has a stronger bond to the floor where tires will constantly be rolling up from one surface to the other. 

Step 5: Thoroughly Vacuum the Surface

As you can imagine, all that scraping, power washing and grinding kicks up a ton of concrete dust, dirt and debris. Before any epoxy goes down, all that has to come off. If not, the epoxy will just encapsulate all that junk, and you won’t get good adhesion.

We thoroughly go over the whole slab several times with an auto scrubber / floor cleaner, alternatively you can mop or pressure wash the floor, but you will need to wait 2-3 days for all that water to dry. I actually make it a rule that the crew has to wear Tyvek suits in this step. That way I can see if they’re kicking up any more dust – if they are, it means there’s still cleaning to do! If you brush your hand over the floor and it leaves a residue on your palm, its not clean enough!

Step 6. Test For Surface Moisture Levels

Next up before going anywhere further, it’s vital I quantitatively test moisture levels within the concrete slab using specialized moisture metering equipment. Rising moisture that gets trapped underneath the epoxy film can cause major bonding issues over 5-10 years. My meters employ electromagnetic and electrical resistance sensors to detect excess moisture below the slab’s shallow surface layer. I confirm fully dry substrates prior to coating.

Conclusion: The Key to Successful Epoxy Floor Surface Preparation

I know this all sounds like overkill. Believe me, I’ve had plenty of customers balk at the level of prep work I insist on for epoxy floor jobs. But I stand firm that following this 6 step process to a T it is 100% worth the time, effort and money.  In my 10 years of flooring experience, all the major epoxy failure horror stories I’ve seen come down to inadequate prep work. Rushed cleaning, lack of profiling, ignored cracks – that stuff will come back to bite you every time.

But take it from me – if you invest in methodical, comprehensive concrete surface prep following steps like I’ve outlined above, you will be set up for epoxy flooring success for years to come. The difference in long term durability and performance is night and day.  When it comes to delivering slick, durable epoxy floors you will be happy with for the long run, there are no shortcuts. Proper concrete surface prep is everything.

While I’ve aimed to provide helpful insider knowledge throughout this guide for those wanting to tackle epoxy flooring themselves, the reality is securing long lasting, professional-grade results often proves extremely difficult without prior experience and the right commercial equipment.

That’s why connecting with seasoned epoxy specialists like myself is the best option for many property owners and facility managers to guarantee you receive incredibly durable, spectacular floors that enhance spaces for decades rather than years for your valuable dollar. My decade in the field coating all types of real world spaces offers peace of mind I can handle any custom job.

And by pairing my systematic methodology with top-tier commercial machinery built for efficiency and safety, I provide premier floor prep services saving clients hours of grueling labors and risk of causing themselves frustrating (not to mention expensive) failures by incorrectly profiling or applying coatings.

So if you have any doubts about tackling involved epoxy processes yourself after reading this, please reach out! I’m always happy to provide transparent quotes and talk through best options for your particular space. Here’s to many more years transforming lackluster floors into dazzling, ultra-resilient epoxy masterpieces together.

 

Brandon Coleman

Brandon Coleman, owner of Garage Designs of St. Louis, brings over a decade of garage transformations and epoxy flooring expertise. A community-focused entrepreneur, he customizes each project to meet unique client needs, ensuring safety, style, and functionality in every space.

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