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RonWC 08-15-2010 04:29 PM

Garage floor paint
I'm in the process of fixing up a house that I own, with the intention of selling or leasing it out in a few months. I have a lot to do and to save money I'm doing everything myself.

The garage floor is in bad shape, stained, pitted, cracked. I'd like to make it presentable. It does not need to be like a showroom floor, just decent and somewhat durable. Saving money and doing it cheap is my primary goal.

Any suggestions on what products or techniques I should be looking at?

kok328 08-15-2010 06:03 PM

I've been wanting to finish mine for years now but, three things stop me everytime.

1) It has a concrete sealer on it and that must come off prior to applying the epoxy coating.

2) It has to be properly prepped and that isn't fun. Degreased with muratic acid wash and a good rinsing.

3) Time and temp/humidity conditions in which to apply the multi-step process.

Nestor_Kelebay 08-15-2010 08:19 PM


I'd be reluctant to paint any concrete slab outdoors. The reason why is that the slab may be open to moisture at the bottom, and so that moisture might be evaporating out the top of the slab. If you cover that slab with an impermeable paint (as every decent floor paint will be), then you're eventually going to get that paint cracking and peeling off as the expanding moisture inside the slab pushes it off.

I'd say that unless and until you know there's no moisture coming up through the slab, it's best to just leave it be.

If you want, in the spring you can get a cheap "hygrometer" (measures relative humidity) from Lee Valley or any place that sells weather stations or hobby supplies. Cover the slab with clear plastic sheeting, slip the hygrometer under the sheeting and weigh the sheeting down around it's perimeter with sticks or a chain or whatever. Watch the needle on the hygrometer. If it gradually rises, then the increase in humidity in the air under the sheet is from moisture evaporating out of the concrete, and you know that the same moisture will cause ANY paint on that concrete to crack and peel off, making your slab an even bigger mess than it is now, and telling every prospective buyer that you CAN'T paint that garage floor because the paint will crack and peel.

Better to have a bare concrete floor than a painted one where the paint is peeling. At least the former doesn't confirm that moisture is migrating through the slab making any paint treatment unfeasible.

GarageGuy 08-18-2010 09:53 AM

You definitely should check the floor for moisture content before coating. You can tape a 2' section of plastic down in several locations of the garage and wait 24-48 hours then lift to see if moisture has collected on the bottom side of the plastic.

Preparation will be the key to having any coating stick. If the floor has lot's of oil stains, this may be the hardest preparation to coating your floors. You will need to lift the stains prior to coating with a degreaser, kitty litter, dawn dish soap, and possibly a pressure washer. Renting a floor buffer with a white scrub pad (approx $25) can really help save time with the process.

One the floor is clean you will need to fill the cracks and the depth and size will determine the correct patching material required for the job. Small pitts and spalls will not be noticed much if you broadcast decorative paint chips on the coating. If you wish to fill them however, you can use autobody filler (Bondo) in shallow pits. It easy to sand it smooth and will bond well.

Finally you need to etch the floor or mechanically abrade the surface. Best to rent a professional floor grinder with diamond grinding stones to profile the surface. If you use Muriatic Acid to etch the floor, neutralize the surface with 1 part ammonia 10 parts water before coating.

RonWC 08-18-2010 08:51 PM

Thank you for the replies, and I apologies for my slow response.

I think I really need to do something with the floor. Leaving it as be is a poor option considering the shape its in. Its awful.

The house is located in a hot humid location, so I realize that it will be temporary before it need to be done again.

One of the reasons I haven't done up to this point is the amount of work that it can be. I've read some articles online and it sounds like a huge job. That's one reason why I'm looking for the best balance between ease of application, versus amount of work. It really doesn't need to be supper great, the finish. It just needs to be presentable.

Nestor_Kelebay 08-18-2010 11:11 PM

I would ask the "Installation Manager" at your local carpet store to ask his installers to save any old thick scrap nylon carpet from people's houses for you.

You can lay that out on your garage floor to cover the appearance of the floor. Scrap carpet is warm and soft so you can work on your car in comfort. It's not slippery when wet or even oily and the mounds of frozen dirt/sand that fall off your car's wheel wells in winter won't cause scratches as they would on a painted floor. And, as a garage flooring, it's fast, cheap and easy to replace. It's really the ideal garage flooring if you get it free and it doesn't cost you anything to dispose of it.

amcraftma 08-26-2010 06:41 AM

Using carpet is also a nice idea. Sometimes when my car needs to be fixed I'm really hurting in my back because I only use a piece of wood to look under my car. What I only see that would go not too nice with it is that when there are spill of oils and dirt from the car.

drewpy 08-31-2010 06:17 AM

Sherwin williams makes several amazing water-based industrial floor products: ArmorSeal Floor Coatings - Protective & Marine

Primers are water-based as well so any possible trapped moisture will be able to escape.

Nestor_Kelebay 08-31-2010 07:23 PM

"Primers are water-based as well so any possible trapped moisture will be able to escape."

"ArmorSeal 700HS waterbased coating, waterbased epoxy topcoat"

Whether or not a coating will allow moisture to escape through it depends on the chemical make-up of the coating, not whether or not it uses water as it's thinner.

For example, the reason why latex paints breathe is because the plastic they're made of actually has large gaps in it. A latex paint resin can be thought of as a long wire scrunched up into a ball. Even though there may be many such balls making up the latex paint film, the spaces between the wires in each ball are larger than individual H2O molecules, but smaller than the average distance between H2O molecule in liquid water. This, H2O molecules can pass relatively easily through a latex paint film, but not liquid water. The ability of H2O molecules to pass through a film is what we call the ability to "breathe".

Whether or not moisture can evaporate through the dry film depends entirely on the chemistry of that dry film, and doesn't depend on whether the coating was water based. Many water based coatings have resins or pre-polymer suspended in water, and those resins or pre-polymer crosslink with each other only when they are in close enough proximity to do that, and that only happens when the water they're suspended in evaporates.

Phone Sherwin Williams tech support and ask if either their water based polyurethane or water based epoxy will still "breathe" once they're fully cured. That's what's important, not whether the coating uses water as the carrier fluid or not.
