Our most popular article warns that we would never apply epoxy to the garage floor, because it's too easy to get it wrong. Exactly what goes wrong, and what happens if you apply it correctly?
Epoxy is amazing for its ability to block water seeping up from below, and to resist dirt, chemicals, and oil that fall on it from above. If any part of the epoxy application goes wrong, the epoxy coating will break away from the concrete, crack, erode, and foster a mold bloom.
While we did say I Will Never Epoxy My Garage Floor (What I Will Do Instead), the fact is that people want to epoxy their garage floors. Let's make sure those jobs come out beautifully, without bubbles, delamination, and loss of adhesion.
Why Consider Applying an Epoxy Garage Floor
One common issue that many homeowners face is moisture seeping into the garage floor.
The water comes up from the ground under the garage floor and seeps to the surface.
The water can lead to garage floor cracks, erosion, and mold, so you might be looking to put a moisture barrier down that will solve the problem.
An epoxy coating is a popular choice for its high moisture blocking and glossy good looks.
Epoxy is a highly durable and resistant material that creates a protective seal that is resistant to scratches, scuffs, and other types of damage.
Epoxy is also highly customizable, with a wide range of colors and patterns available to create a unique and stylish look for your garage.
The Good Side of Epoxy Protection
One of this site's most popular articles is I Will Never Epoxy My Garage Floor (What I Will Do Instead), because our initial response to epoxy difficulties was “not on my watch.”
While we still advocate hiring a professional for epoxy application, it is possible to get a good epoxy floor coating if you're careful and follow instructions.
There are some good reasons to consider epoxy, not the least of which is its stellar performance in blocking moisture. Only solvent-based polyurethane comes close to epoxy's ability to stop water from entering the floor.
Epoxy Has Excellent Moisture blocking Properties
Epoxy sealers create a strong, impermeable layer on the concrete surface.
If you have a membrane moisture barrier installed under the garage slab, an epoxy coating will make the garage floor as close to waterproof as you can hope to get.
Without that membrane, epoxy is still the best defense against unwanted moisture seepage.
Epoxy sealers create a non-porous, impermeable surface that does not allow moisture vapor to escape from the concrete.
Epoxy protects the floor from the freeze-thaw cycle that causes the floor to contract and expand. An unprotected garage floor will crack and spall under this stress.
Fix garage floor cracks to prepare it for an epoxy coating: How Do You Fix Garage Floor Cracks?
Epoxy is a Strong Defense Against Wear and Tear
Epoxy forms a strong bond when applied to a concrete floor.
This bond significantly improves the floor's resistance to wear and tear, abrasion, and impacts from daily activities.
Epoxy provides protection from hot tires, chemical spills, and tools dropped from pegboards.
Epoxy is a Strong Defense Against Solvents and Oils
Oil, gas, and solvents stain and tear away the integrity of the garage floor.
Epoxy coatings are highly resistant to these substances, preventing stains and damage from spills.
This helps maintain the structural integrity and appearance of the floor over time.
Epoxy Provides Slip Resistance to the Garage Floor
You can add slip-resistant additives to epoxy to add traction to the floor even when it is wet or oily.
Additives include sand and fine aggregate that make the floor safer by reducing its slipperiness.
This reduces the risk of accidents and maintains the floor's durability by preventing skids or gouges from slips and falls.
Epoxy Floors are Easy to Clean
Epoxy is the easiest moisture barrier to clean.
It's easier than cleaning floors treated with penetrating sealants, acrylic coatings, polyurethane, and untreated concrete.
Epoxy is resistant to chemicals, gas, oil, abrasion, and wear. It resists dirt, dust, and debris buildup.
Cleaning an epoxy floor does little to wear away at the protective coating. Epoxy floors reduce the wear and tear associated with cleaning and maintenance activities.
The Moisture Risks of Applying an Epoxy Garage Floor Sealer
Applied correctly, epoxy blocks moisture from beneath and protects the concrete.
Applied incorrectly, unhealthy epoxy will cause many moisture-related problems.
If the epoxy is unstable, moisture can get trapped and cause floor damage.
This moisture transmission occurs due to capillary action or hydrostatic pressure.
When trapped water meets an impermeable epoxy barrier, it can cause various issues, such as delamination, blisters, bubbles, efflorescence, mold, or mildew.
I can't stress enough how important it is to dry out the floor before applying any coating: Can You Really Waterproof a Garage Floor?
Unhealthy Epoxy Can Cause Garage Floor Delamination
If moisture is present in the concrete when the epoxy is applied, or if moisture accumulates beneath the epoxy layer over time, it can weaken the bond between the epoxy and the concrete.
The trapped moisture can cause the epoxy to lose its adhesion to the concrete, which separates from the epoxy.
This delamination shows up as peeling and lifting off the garage floor.
Unhealthy Epoxy Can Cause Garage Floor Spalling and Cracking
An unhealthy epoxy application that traps moisture will contribute to the deterioration of the concrete over time.
It can lead to spalling, cracking, or the breakdown of the concrete itself.
Need to fix the spalling and pitting next? Or even find out that that's what these damaged areas are called? Read our article: How Do You Fix Garage Floor Spalling and Pitting?
Unhealthy Epoxy Can Cause Garage Floor Efflorescence
Moisture vapor can carry salts and minerals from within the concrete to the surface, where they may crystallize and form a white, powdery deposit known as efflorescence.
This can be unsightly and may weaken the bond between the epoxy coating and the concrete surface.
Unhealthy Epoxy Can Cause Garage Floor Mold and Mildew Growth
Trapped moisture can create a conducive environment for mold and mildew growth beneath the epoxy coating, which can lead to unpleasant odors and potential health concerns.
How to Avoid Excess Moisture Epoxy Failures
To prevent epoxy failures, follow the application instructions to the letter. Take the following steps before applying an epoxy coating.
Test the Concrete's Moisture Level
Conduct a moisture test before applying the epoxy. The floor must be dry enough for the epoxy to adhere properly.
There are several methods for testing moisture levels, including calcium chloride tests and relative humidity tests.
Diagnose the Moisture Source
If the moisture levels are too high, take the necessary steps to address the problem before proceeding with the epoxy application.
Determine the cause of the moisture problem in the concrete.
Common sources include:
- groundwater seepage
- poor drainage
- leaky pipes
- inadequate vapor barriers beneath the slab
Dry Out Concrete to Accept Epoxy
You can take the following steps to address the concrete moisture issue and prepare the slab for epoxy application.
Allow Concrete to Cure and Dry
New concrete takes at least 28 days to cure. Give the concrete adequate time to dry before applying the epoxy coating.
Depending on the severity of the moisture issue and the environmental conditions, this may take several weeks or even months.
It is important not to rush this process, as applying epoxy to a moist concrete surface can lead to delamination and other problems.
Improve the Drainage Nearby the Garage
Ensure that the area surrounding the garage has proper drainage. This will prevent water from pooling near the garage or under the slab.
This may involve redirecting downspouts, installing French drains, or grading the landscape to direct water away from the foundation.
Install an Above Ground Vapor Barrier on the Garage Floor
A vapor barrier can help prevent moisture from seeping up through the concrete slab.
Although it is most effective when installed during the construction of the garage, you can still add a vapor barrier on top of the existing floor.
This usually involves laying down a thick polyethylene sheet or specialized vapor barrier product.
This is followed by an additional layer of concrete or underlayment to protect the barrier.
This additional layer provides a suitable surface for the epoxy coating.
Apply a Concrete Sealer or Moisture-Blocking Primer to the Garage Floor
Apply a penetrating sealer or a moisture-blocking primer to the garage floor.
These reduce the moisture that migrates up from the concrete slab.
Sealers penetrate the concrete, creating a barrier that minimizes moisture migration.
Primers block the moisture with a rubbery-plastic coating.
These products are designed for damp concrete application.
They can help seal the concrete and prevent moisture from affecting the epoxy coating.
Use a Breathable Epoxy on the Garage Floor
Another option is to use a breathable epoxy coating that tolerates the extra moisture.
Some epoxy products are designed to be more breathable, which allows moisture to escape from the concrete without compromising the bond or performance of the coating.
Breathable epoxy coatings or alternative breathable coatings, such as silane or siloxane sealers, can be more suitable for damp concrete surfaces.
Improve the Garage Ventilation
Increase the ventilation in the garage to promote the drying of the concrete.
Open windows and doors, and use fans and dehumidifiers to help remove moisture from the air.
The less moisture in the garage translates to less moisture in the slab because the low humidity allows the slab to eject excess vapor.
Cut Your Epoxy Floor Losses
If addressing the moisture issue proves to be difficult or costly, you might want to explore alternative garage flooring options.
You'll need a solution that is more suitable to damp conditions.
These options may include:
- interlocking garage floor tiles
- rubber mats
- ventilated garage floor systems that allow moisture to evaporate
Addressing the moisture issue caused by groundwater beneath the concrete slab is crucial for the successful application and long-term performance of an epoxy coating. By taking the necessary steps to manage moisture and selecting appropriate products, you can help ensure a durable and attractive garage floor.
How to Prepare the Floor to Accept Epoxy
If you've conquered all the moisture problems, now it's time to prep the concrete for an epoxy bond.
Surface preparation is essential, and includes cleaning, etching, and possibly grinding the concrete before application.
Failure in any of these steps can lead to a damaged floor.
Epoxy Skills You'll Need to Master
Epoxy is second only to solvent-based polyurethane for how hard it is to apply. Epoxy application is hard to get right, and easy to get wrong.
Laying down even layers of the epoxy film is difficult as well.
Epoxy requires careful mixing of the resin and hardener. Once mixed, the active epoxy has a limited “pot life.” You have a short period after the epoxy is mixed before it hardens. You must get it onto the garage floor surface in thin, even layers before the mixture is too hard to apply.
Mastering these skills before epoxying the garage floor will go a long way toward creating a healthy bond.
Clean the Floor
Thoroughly clean and prepare the concrete surface to ensure proper adhesion of the epoxy coating.
Remove any dirt, debris, and dust from the garage floor using a broom or vacuum cleaner.
Pay special attention to corners and edges where dirt and debris can accumulate.
Remove Oil and Grease Stains from the Floor
Use a degreaser or a specialized concrete cleaner to remove any oil, grease, or other stains from the surface.
Follow the manufacturer's instructions for application, and rinse the area thoroughly with water afterward.
Allow the rinse to dry thoroughly, as water will interfere with the epoxy bond.
Repair Cracks, Spalling, and Holes
Inspect the floor for any cracks, spalling, pitting, holes, or other damage.
This may involve grinding or acid etching to remove broken concrete pieces.
I put the details of how to repair the concrete cracks here: How Do You Fix Garage Floor Cracks?
Use a concrete repair product, such as epoxy filler or hydraulic cement, to fill and repair these imperfections.
Level any uneven areas with a concrete repair product.
Do not skimp on curing times. Wait until the repairs are fully set before applying the floor coating.
Test for Existing Sealers
To determine if there is an existing sealer on the floor, pour a small amount of water on the surface.
If the water beads up or does not absorb into the concrete, there may be a sealer present.
In this case, you will need to remove the sealer through grinding or chemical stripping before applying the epoxy.
Profile the Concrete Surface
Profiling is the prepping of the surface to accept a bond.
Profile the concrete floor using acid etching or diamond grinding.
Acid etching involves applying a solution of muriatic acid and water to the floor, which reacts with the concrete and opens up its pores.
Grinding is a mechanical method that roughens the surface and creates the necessary profile for epoxy adhesion.
Neutralize the Floor, Rinse, and Allow the Floor to Dry
If you used acid etching, neutralize the surface with a mixture of baking soda and water or a commercial neutralizing solution.
Then, thoroughly rinse the floor with water to remove any residue from the etching or cleaning process.
Allow the floor to dry completely before proceeding.
Optionally Apply a Primer to the Floor
Some epoxy systems recommend applying a primer to the concrete floor before the epoxy coating.
A primer can help improve adhesion, provide a more even and consistent finish, and increase the durability of the epoxy coating.
If using a primer, follow the manufacturer's instructions for application and curing times.
Do you feel ready to epoxy your garage floor?
Did you conquer the moisture issues, ventilate the garage, repair the cracks, and master the skill of laying out thin layers of epoxy?
Good luck with the project, and here's to excellent epoxy bonds!