Epoxy Floor Repairs

1.) Homeowner-applied epoxy flooring systems: These are usually one-part water based epoxy $99 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 epoxy system and a two-part epoxy system. A one-part system is essentially paint. It sits on the surface of your floor until the water or solvent evaporates and the remaining solids dry. A two-part epoxy system has a Part A resin and a Part B hardener. When they are mixed they interact chemically, sink down deeply into the concrete surface and create an extremely tough surface.

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.

1.) Peeling of the epoxy surface - usually under where the tires sit.
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.
6.) Epoxy won't cure - still sticky.
7.) Numerous oily, black or rust colored spots the size of a dime or quarter.

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:

Cleaning:
Scrub the floor thoroughly with a cleaner/degreaser product like Krud Kutter, Simple Green or even Dawn dish washing detergent. Scrub the cleaner/degreaser into the surface with a stiff brush, wash it off thoroughly with your garden hose and allow it to dry thoroughly. Using a leaf blower or a fan will speed up the drying process.

If the problem was white powdery efflorescence, scrub it down well with common household white vinegar 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 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.

More supplies:
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. After dampening the crack or hole, fill it 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 and stained 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.

Concrete Lifting:
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.

Peeling Coating:
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 their use, they can easily get away from you and tire you out quickly from battling them.

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 'bump'.

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. 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 it will finally cure on its own. If the problem was temperature related, hopefully the temperature has come up and the epoxy will cure properly. (Don't try using a fan. Epoxy doesn't dry like wall paint. It cures at appropriate temperatures.)

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. It will burn your skin. 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.

Numerous 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.

Then the previous floor coating will need to be ground off with a diamond grinder and to be coated with a high quality moisture barrier product. We use Versatile Building Products' 4100 epoxy moisture barrier: www.garagecoatings.com. The floor can then be recoated with colored epoxy, chips and sealer.

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.

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 urethane or 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.

Peeling:

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 those other areas in the future.

California Concrete Restoration, Inc.
Laguna Hills, CA
(949) 939-4088

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calconcrete@cox.net