Epoxy Floor Repairs
Best techniques for repairing an epoxy floor
Repairing a damaged epoxy floor isn't too difficult. You DO need to be aware of what materials were used on the floor originally. Some patching materials may not be totally compatible. They may not stick to or blend well with the existing coating.
Matching the existing materials and properly preparing the damaged floor for repairs are critical steps. If you ignore either of these steps you are going to have problems in the future. This may include having to grind off the whole floor and having to re-coat it again.
Types of epoxy garage floors
Know what you started out with
1.) Homeowner-applied epoxy flooring systems: These are usually $99 one-part water based epoxy paint kits from a local hardware store or chain store. They almost never supply a tough, clear surface sealer and give little instruction on proper surface preparation.
2.) Professionally-applied epoxy flooring systems: Professional installers have the appropriate equipment and experience to properly prepare the surface and use industrial-grade, two-part epoxy and resin-based sealer materials. This assures you of maximum durability and appearance for your floor.
There are major differences between a one-part water based epoxy system and a two-part resin based epoxy system. A one-part system is much like wall paint. It sits on the surface of your floor until the water evaporates and the remaining solids dry. A two-part epoxy system has a Part A resin and a Part B hardener. When the components are mixed they interact chemically, sink down deeply into the concrete surface and create an extremely tough surface. It 'cures' rather 'drying' like a water-based paint does.
Not all of these coating systems are compatible in terms of adhesion, durability, thickness or appearance. For repairs, you need to stick with the manufacturer of the original materials . . . or at least in the same family . . . in order to ensure a satisfactory outcome.
If you have a professionally applied floor coating, by all means contact the original contractor first. They will have the compatible materials and experience to do the repair properly. The repair may even fall within their warranty.
Epoxy floors fail for a variety of reasons
1.) Top of the list is inadequate floor preparation. Epoxies and sealers cannot adhere to a non-porous surface.
2.) Inexpensive water-based epoxies with only 20-30% solids just are not up to the job of resisting 'hot-tire pickup' and repelling stains from auto fluids.
3.) Bubbling from water intrusion from under the slab needs to be addressed (see below).
4.) Color fading: (see below).
Problems you might have to deal with
1.) Peeling of the epoxy surface - usually under where the tires sit. (This is called "hot tire pickup")
2.) Oil, transmission fluid, battery acid and brake fluid stains.
3.) White water stains or dusty white efflorescence powder, crumbling stem walls or constantly damp areas.
4.) Fading or yellowing of the surface in areas that get direct sun.
5.) Cracks that reappear or lifting of the concrete around cracks or expansion joints.
6.) Epoxy won't cure - still sticky.
7.) Oily, black or rust colored spots or blisters the size of a dime or quarter.
How to get the repair done
If your epoxy garage floor was installed by a professional installer, call them first to fix the problem. They have the experience, tools and compatible materials to best deal with the problem. Unless the problem was caused by extreme conditions, the repair will probably be covered by their warranty.
If your floor is coated with a home-owner installed product, at least follow these steps:
Scrub the floor thoroughly with a stiff brush using a cleaner/degreaser product like Krud Kutter, Simple Green or even Dawn dish washing detergent. Wash it off thoroughly with your garden hose and allow it to dry thoroughly. You can use a leaf blower or a fan to speed up the drying process.
If the problem is white powdery efflorescence, scrub it down well with common household white vinegar (available at your grocery store for about $3/gal) and a stiff brush. Rinse and allow to dry thoroughly. The white powder is evidence of water coming up through your concrete slab and bringing minerals up along with it. The problem could be sprinkler water from a planter box adjacent to the garage seeping into and under the slab. It could be a ruptured water line under the slab. You REALLY need to eliminate the source of the water problem or your surface repairs will undoubtedly fail again in the near future. Have a landscaper and/or plumber come in to look at the water intrusion problem and give you a solution. The seepage could also cause serious mold damage to the interior walls in your house.
Buy another $99 hardware store epoxy floor coating kit. You probably won't need much of the kit for the repairs. The kit will go bad over the next few months after you open the containers so don't plan on using it again.
Cracks, chips, faded and stained areas:
If the problem is a crack, rent a 4" angle grinder with a thin diamond cutting blade (or 1/4" 'crack chasing' blade) from your local hardware store or tool rental yard. If the problem is a surface flaw, rent a 4" angle grinder with a diamond cup blade. If the area to be repaired is more than a few linear feet or square feet, it is highly advisable to rent a grinder with a dust hood and attached vacuum. The fine dust from the epoxy and concrete can be messy and is certainly not good for your lungs.
Cracks and holes or chips: Use the grinder to cut down into the crack or hole about 1/4" wide (for cracks) and about 3/8" deep. The resulting sides of a hole should be vertical, not sloping up to the surface. Dampen the the crack or hole well with a sponge but don't leave any standing water. Fill the crack or hole with an acrylic-modified cement patching compound. Smooth the surface by using a trowel or disposable plastic putty knife and then use a damp fine grained sponge to pat it smooth. You may need to spritz it down with a little water from a spray bottle to get the patch quite smooth. This should eliminate the need to grind the patch smooth when it is cured. Let the patch cure for the amount of time recommended by the manufacturer of the product. (Deeper patches will remain dark and take longer to cure.)
Faded, stained or yellowing areas: If your epoxy floor was coated with a high quality UV-resistant sealer, this should not be a problem. If not, you will need to grind off the problem areas . . . or the whole floor . . . and start anew.
It is best to hire a professional to grind down lifted areas. It usually takes heavy grinding to remove the "lip" and to reduce the trip-and-fall hazard. They will have the appropriate equipment and know how to feather out the edge so as to not weaken the slab.
Use a 4" diamond cup grinder to lightly take off the peeling areas out to about 1" beyond the damaged area - down to bare concrete. The goal is to get the surface about as rough as 100 grit sandpaper so the epoxy will be able to sink in and stick. Be sure to keep the grinder level when using it. Tilting the grinder will create swirl marks in the surface which will then need to be patched. If you are going to grind more than a few square feet it is highly advisable that you rent a grinder with a dust hood and attached vacuum.
Re-coat the treated areas with the kit materials.
Clear Sealer coat repairs:
If the only problem was with the sealer coating flaking and only in spots, lightly sand the area(s) with 80-100 grit sandpaper. The goal is to get rid of any flaking sealer and to provide some micro scratches for the new sealer to bond to. Avoid sanding into the chips and underlying epoxy. If the area to treat is large, you should rent a floor buffer with a very course plastic fiber pad (they are usually black). Have the rental company instruct you on the proper methods for controlling the buffer. If you are not familiar with the buffer's use, it can easily get away from you and quickly tire you out from battling it.
If the sealer problem involves yellowing or blushing white, you will probably have to carefully grind off those areas with a diamond cup grinder down to the epoxy and chips. Be careful! It is easy to go too far with the grinder and then you will have an epoxy/chip repair problem to deal with also.
On small areas you should thin the sealer so it will blend in with the surrounding areas and not create a hump. Check with the supplier of the sealer to determine an appropriate solvent. Usually it will be acetone or xylene. We normally use a dilution ratio of 6-8 parts sealer to 1 part solvent. We also pat down the mixture using a clean rag rather than using a brush or a roller (wear gloves). That minimizes the problem of putting down too much sealer on the patch and creating a 'hump'.
If the area to treat was the whole floor, just re-roll the whole area with 100% sealer after sanding or buffing.
Epoxy won't cure - still sticky:
There are three probable causes. 1.) The epoxy wasn't mixed enough before application. Manufacturers usually recommend 2-3 minutes of vigorous mixing with a drill and mixing paddle to make sure that the components blend together thoroughly. Using a paint stick and stirring by hand usually won't do the job. 2.) There was some residual acid or water left over from the cleaning process which inhibited curing of the epoxy. 3.) The temperature of the slab was under 50 degrees at the time of application.
Best solution: Wait about a week to see if the epoxy will finally cure on its own. If the problem was temperature related, hopefully the temperature has come up and the epoxy will cure properly over time.
Worst case: If the epoxy still doesn't cure after a week it probably never will. You will then have to use an epoxy/urethane stripper. The most effective ones contain Methylene Chloride, a strong solvent. (Home Depot sells one under the trade name of Jasco which is in a gold and red can. Use the gel version rather than the diluted spray and follow the instructions.) Methylene Chloride is effective but is nasty stuff and it will burn your skin. (Keep a 5 gallon bucket of water or a hose handy to wash off this material if you use it.) If you want to use an eco-friendlier product, look at www.franmar.com for their Soy Gel product. It is more expensive but it won't hurt you or the environment.
Oily, black or rust colored spots.
This normally indicates a water intrusion problem from underneath the slab. There is really no quick fix for this problem. The water intrusion problem will need to be fixed first. Check with a landscaper to see if the water is coming from the yard and if drains need to be installed to divert the water. If that's not the problem, check with a plumber to see if you have a leaking pipe under the slab. Neither fixes are cheap but are very necessary. (The water is probably also invading the walls of your house causing rot and potentially dangerous mold.)
When the water problem has been fixed and the slab allowed to dry out, the previous floor coating will need to be ground off with a diamond grinder and then be coated with a high quality moisture barrier product, decorative chips and sealer. We use Versatile Building Products' 4150 epoxy Vapor Stop at
Minimizing future problems
Let's try to not have to do this again
Cracks, fractures and lifting:
Your epoxy floor coating is not a Star Wars force field. When tens of tons of a concrete floor want to move . . . or if you drop an engine block on the floor as one of our customers did . . . nothing is going to stop the damage. The underlying concrete will fracture and/or crack and will undoubtedly damage the coating and will necessitate a repair.
Fading and staining:
You should really consider putting down a clear, UV-resistant, non-yellowing sealer over your epoxy floor. This will make it MUCH easier to clean, will resist automotive fluid stains and will protect it from fading or turning white or yellow.
Hardware stores generally don't usually carry sealers that are appropriate for going over epoxy floors. Check with a paint store that serves contractors: Sherwin Williams or Dunn Edwards. Or contact our supply source, Versatile Building Products at http://www.garagecoatings.com. The products they recommend will probably be a UV-resistant urethane or a polyurea sealer.
You will need to lightly sand down the whole floor with 80 or 100 grit sandpaper with an orbital sander or a pole sander to achieve a surface that the sealer can readily bond to. The goal is to scuff up the surface and make it look a bit dull but not to totally remove the old coating. Put down a light coat of the sealer and sprinkle down matching decorative chips to cover the faded or stained areas. When it is set, lightly sand or scrape the chips and put down a final coat of the sealer.
The areas you repaired by grinding and applying new epoxy and sealer should be fine. The new sealer coat over the rest of the floor may eliminate future peeling but if the original epoxy base coat didn't adhere properly, you could have problems in other areas in the future.
If the damage is only a tiny spot
1/4" or so
Lightly sand the area with 100 grit sandpaper to remove any loose material and any lifted edges. Hopefully your original installer left you with a few pounds of excess decorative chips from the job. Lightly coat the area with some gel-type Krazy Glue and smooth it down with a piece of paper - don't use your finger. Immediately sprinkle down a light coat of chips (probably no more than a thin pinch) onto the Krazy Glue. Then go back inside and relax.
The Krazy Glue will probably set up in an hour or so and there is no need to rush.
When you are ready to tackle the job again, sweep off any excess chips, sand down the surface again if it is too rough and apply a top coat of Krazy Glue (again use the paper to smooth it and not your finger).
Note: This technique is not recommended for large or numerous damaged areas.
California Concrete Restoration, Inc.
Laguna Hills, CA
Check out our other related web pages below
Other links about epoxy floors
- "The Truth about Epoxy Garage Foors"
Click to see our free report
- Proper floor preparation
The proper way to prepare a floor for an epoxy coating
- The differences in materials used for epoxy floors
What to use and what not to use
- Epoxy floor durability
How long will it last?
- Maintaining an epoxy floor
Tips & techniques