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Garage Floor epoxy

I want to paint my attached garage floor with epoxy paint. The floor is made of 4 concrete sections separated by expansion joints that are about 1/2 in wide and deep. The slabs are smooth and have no cracks. But there is a crack in the concrete at the bottom of one of the expansion joints. Do I have to seal or patch the crack before applying the epoxy? If so, how is the best way to do this? Do I epoxy down into the expansion joints? Or do I just epoxy the flat surfaces and leave the expansion joints open and untreated?

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Posted 2011-04-01T03:09:27+0000  by macmil macmil

Hello macmil and welcome to The Community!  We want to help you paint your attached garage floor and have some answers for you.  I contacted Behr Technical Support (1-800-854-0133) to help with the concern about the expansion joints.


You should repair the crack at the bottom of one of the expansion joints first - before applying the epoxy.  (The expansion joint is used for weight distribution.)  Use a filler to repair the crack.  The store associates in the paint department can assist you with selecting the best filler to use.   


You can then epoxy down the expansion joints and the flat surfaces.  The epoxy will stay on top if the joint is filled.  Do not leave the expansion joints open and untreated. 


There is an excellent Project Sheet at Behr’s website on “How to Prepare and Coat a Concrete Surface.”  You will also find a list of recommended products and suggested equipment needed to complete the project. 


If your concrete is bare, you should clean and etch the concrete using Behr’s Concrete & Masonry Cleaner/Etcher NO. 991.  Make sure that you completely scrub and rinse – rinse – rinse when using this product. 




You will then need to bind the topcoat to the concrete with a primer using Behr’s Concrete & Masonry Bonding Primer NO. 880.


880 Behr.jpg


If the concrete was previously painted, you will need to strip off the old coating using Behr’s Concrete & Masonry Paint Stripper No. 992 then scuff sand the concrete.




If you have severe stains, you may also need to use the Behr Concrete & Masonry Cleaner/Degreaser No. 990.




All of this preparation will create a fabulous foundation (no pun intended!) for your paint layer.  I recommend applying the 1-Part Epoxy Acrylic Concrete & Garage Floor Paint since it is made for household use.  It is a heavy-duty, multi-surface coating that provides a durable and long-lasting finish.  There are 38 custom colors and computer matching is available. 





For additional slip resistance, consider adding Decorative Color Flakes or a Non-skid Floor Finish Additive No. 970.


69b8b991-302d-467d-9c3b-173357f5bfee_300.jpg      679e60c3-cafa-4ff2-8e1b-9e1d37e7ff96_2.jpg    



(Note: Behr also makes a Premium 2-Part Garage Floor Coating which made for industrial or commercial usage, has better durability, lasts longer, and is stronger.) 


Best wishes on the garage floor project and please keep us posted on your progress!


Posted 2011-04-01T14:40:12+0000  by Eileen_HD_ATL

I wish I'd read this sooner.  We just had our garage floor coated with epoxy yesterday.  I expected the cracks to be filled in by the epoxy...I was wrong.  I still want the cracks filled in and the epoxy on top.  What do I need to do from here?  Can I apply filler on top of the epoxy and then reapply epoxy over the filler or do I need to strip the epoxy in the crack, fill it and then reappy?  In either case, will the new expoxy join well with the old?  Thanks!

Posted 2011-10-22T10:54:29+0000  by DepotLou

I doubt that you'll have much luck covering the cracks or with the epoxy sticking to the existing epoxy.  Those kits work well if there's no damage, but they don't cover anything.  I wouldn't recommend doing anything to it now.

Posted 2011-10-24T21:22:16+0000  by jhutch

Hello DepotLou and thank you for joining our discussions.  We are glad that you are here.


You are right, jhutch, there may not be much success in either covering the cracks or with new epoxy sticking to the existing epoxy.  (Welcome to The Community, too!)


I am assuming DepotLou that you used the 1-Part Epoxy Acrylic Concrete & Garage Floor Paint.  The instructions below will fill the cracks and finish your garage floor but you will need a little time to get the finished results.  (Note: If you used Behr’s Premium 2-Part Garage Floor Coating, the following instructions will not work for you.  Please contact me for help with that product.)


You will need to remove the epoxy from the area around the cracks, sand to the bare concrete, and fill in with masonry filler (patch).   Your local store can recommend a Quikrete product that is best for you.  Let the surface cure for 30 days or as recommended by the manufacturer.


Perform a water test to ensure a porous surface:  sprinkle water over the area that was filled in over the cracks.  If the water is absorbed in a few minutes, you have passed the water test!  If the water is not absorbed, etch the surface with Behr’s Concrete & Masonry Cleaner/Etcher NO. 991 and rinse thoroughly (following the manufacturer’s recommendations); let dry before proceeding.  


If necessary, use the Behr Concrete & Masonry Cleaner/Degreaser No. 990 to remove any stains.


Next you will need to prime using Behr’s Concrete & Masonry Bonding Primer NO. 880.  Now you are ready for the 1-Part Epoxy Acrylic Concrete & Garage Floor Paint.  Blend the new epoxy into the existing areas.  You may want to apply a thin coat over the entire surface to even the finish.   Be sure to apply Decorative Color Flakes or a Non-skid Floor Finish Additive No. 970 if previously applied over the surface.


Let dry for 72 hours before allowing foot traffic and 7 days before parking the car.  If the temperature is cool (below 60oF) or there is high humidity, you will need to allow the surface to dry for a longer period of time. 


Best wishes on your project and please keep us posted on your progress.  Thank you for joining The Community.


Posted 2011-10-25T20:42:02+0000  by Eileen_HD_ATL
I would recommend always using the cleaner/degreaser... Even if a surface has never been driven on (tires are a petroleum product that drive on asphalt, a petroleum product, those same cars drop oil, a petroleum product, you get the idea) trees and plants have natural oils in their branches, bark, leaves, blossoms and fruit. The cleaner/degreaser or the cleaner/etcher will take care of any of it. When using that bonding primer, only put it on bare concrete. Where you have the existing paint at the edges of your expansion joints, you can scuff it with sand paper to help give it more tooth if you think you're going to overlap a bit onto the painted edge.
Posted 2011-11-06T12:21:06+0000  by Paul



Reading your post clears up some questions I had about redoing my garage floor. I just wanted to ask a bit more. My garage floor is painted and getting old. I power washed it and removed much of the old loose paint. I wanted to apply the 2-part epoxy paint but berfore I do, can I just sand down the old painted surface to ruff it up and then power wash it again before painting, or do I need to add the topcoat primer?


I read some horror stories of the paint not sticking and I wanted to make sure to do it right. Although I was hoping I did not have to completely strip the floor...?


Thank you,


Posted 2012-05-21T03:16:10+0000  by jh23

You can rent a floor grinder from your local THD (guessing around $100) and just take it all down to bare concrete. Then you're assured of getting a good bond of the epoxy to the floor. Yes it will be a bit more work, but in the long run, it will pay off.


I've never liked putting a garage floor coating over an existing coating. The existing coating is the foundation of the new layer. If it's not in good shape, you've just wasted your time and money. In my view, garage floors are one of the more difficult things to paint. Not only do you have normal foot traffic, but you have a two ton vehicle on it, with four hot tires. Not to mention all the stuff that drips off that vehicle, such as salt and petroleum products.


Maybe ordjen will weigh in on this topic with some of his insight.

Posted 2012-05-21T03:34:00+0000  by Paul

Hello Jeff and thank you for joining The Community!  We are glad that you are here.


Paul is right – garage floors can be a challenging surface to paint and maintain.   Patience and proper preparation will pay off.  Be sure to use proper personal safety equipment (safety glasses, gloves, a mask or respirator (if you are sensitive), and wear long pants and a long-sleeved shirt).   


The Home Depot has 2 kits that use the 2-part process: Behr and Rust-Oleum.  I spoke to the Technical Teams for both companies to get their responses and selected best practices for your garage floor.  Be sure to completely follow the manufacturer instructions for the product you select since there are differences between the products. 


Here are the helpful tips provided by the respective vendors:



Behr 2 part GF epoxy.jpg

(Technical Support 1-800-854-0133 x 2)


The Behr 1-Gallon Premium 2-Part Epoxy Garage Floor Coating is a store exclusive product.  It is available in 1 gallon gray or tan.


As long as the previous coating is not peeling, you are good to go.  Rough up the surface with steel wool or a wire brush (sandpaper is okay but may be a slower process).  Use the Etcher only on bare concrete patches (apply, let set 10-20 minutes, then THOROUGHLY rinse off).   You do not need a floor primer; you can then paint on the surface. (Note: Bonding Primer is sold separately and used with the 1-part floor coating system.)


Be sure to check that the environmental conditions are 50-80oF and less than 50% humidity.  The painted surface will dry to the touch in about an hour.  If desired, you can coat with a wet look product after 4 hours (waiting 24 hours or longer will give better results).  Use a fan to help dry the surface.


Light foot traffic can enter the surface in about 6-8 hours while heavier traffic should wait at least 24 hours.  You can drive on the surface as soon as 3 days , but the heat from the tires  has the potential to lift the surface.  It is best to wait several more days under the proper temperature and humidity conditions for best results.



Rust-Oleum 2 part GF Epoxy.jpg

Rust-Oleum EPOXYShield® Solvent-based Epoxy Professional Floor Coating
(Technical Support 1-877-385-8155 x 4)


Rust-Oleum EPOXYShield 2-Part Epoxy Garage Floor Coating Kit is a store exclusive product.  It is available in 1 gallon semi-gloss tan as well as 2 gallon high-gloss gray or tan.


Make sure the floor is clean and dry.  Use a wire brush to remove any loose or peeling paint or stain. If any existing areas lift or peel, the new garage floor coating will also lift and peel.  Scuff sand the floor with 60 grit sandpaper.  Rinse thoroughly. 


A floor sander  is an excellent option to get the surface down to the concrete layer.  Be sure to remove the dust and dirt (mop, rinse, and dry).   You do not need to etch if using the floor sander.


Once the floor is fully dry, apply the epoxy over the garage surface.  Apply in conditions that are 55-80oF and less than 85% humidity.  You can walk on the surface in 24 hours and drive on the surface in 4 days.  You will achieve better results if the floor can dry longer.





Best wishes on your project and please keep us posted on your progress!


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Posted 2012-05-22T18:48:40+0000  by Eileen_HD_ATL

We had the Rustoleum Epoxy coating applied to our garage floor in August of 2007. The installation was done by one of HDs subcontractors. shortly after the "extended 3 year" warranty expired, the epoxy in the center of the floor began bubbling up. We now have an area about 12' in diameter that is bubbled up and cracked. Is there a fix for this?

Posted 2012-09-13T14:27:22+0000  by kennyray

I would contact Rust-Oleum. It is my understanding that the garage floor coating done through Home Depot's In-Home Services group was a completely different coating than what is sold in the stores. The moderators will correct me if I'm wrong. I believe it was an industrial coating (not water-based) versus the residential grade stuff (water-based) sold in the stores, therefore a completely different animal.

Posted 2012-09-14T19:37:29+0000  by Paul
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