Fixing/leveling concrete floors prior to epoxy?

greenbuggy · Nov 30, 2017

Considering doing the epoxy thing to my semi-unfinished basement and garage floor to make it easier to clean and look a little nicer.

I'm sure I'm not the only one who has considered doing this, nor do I think I'm the only one with some imperfections in the floor I'd like to coat, so I'm curious for anyone who has -
Is there any preferred method of patching up the floor prior to laying epoxy over it? My basement has a few spots where some of what I'm guessing were redheads were driven into it and ripped up later, which took out much more than just a nail-sized spot, in some cases as much as an inch deep and couple inch wide "crater". A recent trip to one of the home improvement stores showed a kit from the same brands that were selling concrete floor epoxy sets for patching imperfections but it was expensive, IIRC almost $30 for less than a quart worth of patching material and I think I'd probably need a few hundred bucks worth of those kits in order to take care of all the spots I would like to be level before putting a coating over it.

So I'm curious, if you're going to end up coating with epoxy anyways, is there any reason to not blow the craters out with an air gun, mix up some quikrete and use that as patch material? Seems like most people shy away from that because of possibility of different color shade or slight texture/appearance difference. Do any additional precautions need to be taken to ensure adequate adhesion between the existing concrete and the patch material?

Beyond that, I'm sure there's people here who have coated floors many thousands of square feet more than I'll end up doing, but still curious - any more economical options than what the home improvement stores are offering? Seems like they're averaging about $120 for enough to do a light coat in a 1-stall garage and I'm guessing that somebody, either a local paint supplier or an internet purchase will have a lot more economical option if I'm buying a 5 gallon pail of the stuff rather than a bunch of small containers and redundant packaging.

72bwhite · Nov 30, 2017

concrete shrinks you can use floor leveling mix
a building material supply yard would carry larger sizes on the floor patch

bhigdog · Nov 30, 2017

If you are going to spend the $ on a good expoxy coating don't skimp on a repair that will fail. Use the epoxy filler. Also your floor should be prepared for painting. Either shot blasted or acid etched to give the paint a good "tooth". 20 years ago I did my 32 X 48 shop floor with a Valspar 2 part epoxy paint (NOT water based). I've put it through hell and it's still in good shape. I'm sure there are many good epoxy coatings but at the time Valspar was was the best buy........Bob

no704 · Nov 30, 2017

A buddy of mine runs a floor coating co. He uses Bondo to patch concrete.

Mark Rand · Nov 30, 2017

As the above two have indicated, use an epoxy or styrene based repair cement rather than a fairly weak mortar mix (AKA Quickcrete). Keying the craters for a better bond won't do any harm.

Terry Keeley · Nov 30, 2017

I did my basement and garage a dozen years ago and it's still in great shape today. Wanted to do it "right" so I rented a shot blaster to prep the concrete which in turn opened up many fine cracks. I was advised the best way to fill them was with a good epoxy and "cabosil" filler. Two coats of epoxy primer and two coats of two part polyurethane and it came out great.

I would find a good composites or industrial coatings supplier in your area rather than using the big box stuff, it's a lot of work and you want it to last...

DMF_TomB · Dec 1, 2017

in basement where floor by chimney was low spot and sometimes water would collect i put in ceramic floor tile.
.
drainage trench by walls needed to be deeper but easier to make floor higher with ceramic tile. you can lay tile cement heavier if you want tile a bit higher. i use 4 foot level for straight edge to try to make floor flatter
.
tile makes basement look cleaner

boslab · Jul 3, 2023

We use self levelling compound over here, like febfloor or similar.
Mix pour and trowel it a bit, it sets flat.
Works well ( usually)
Mark

rons · Jul 3, 2023

If the holes are that large just float in some concrete with large rocks removed.
First fill holes with water for however long it takes to hold a puddle. Makes sure the wet from the concrete doesn't get sucked away.

rimcanyon · Jul 3, 2023

If you have a Whitecap (HDS) store nearby, they carry the Ardex line of products. Ardex makes a self-leveling product called K301 that works great. We used it to level our garage slab and it has held up inside and outside for 5 years. You can't tell where the bare concrete is and the Ardex patch is, it is that good a match.

greenbuggy · Jul 14, 2023

yomav said:
Most of the epoxies I've seen will only correct up to half an inch or so. What long-term options exist for correcting low spots that exceed 1 inch? The garage will be used for parking cars and DIY auto maintenance. Am I overthinking this and I should just get the floor coated? It doesn't need it to be perfectly level, but it's just much worse than I've seen before.

How big is the area where you have 1-2" of water pooling?
In my experience leveling compound is mostly often used beneath actual flooring, it doesn't respond well to any movement and you're talking about putting some heavy items (cars) on top of it, plus probably some twisting forces due to steering your vehicle over it

"level" is usually not as important as "flat", especially in a garage application where you would probably prefer to have any rainwater or snowmelt off the vehicle drain away, rather than staying in place underneath it. I'd be figuring out if this is something you can hire out to have corrected by someone who grinds and repairs concrete.

Another thought is could you have the concrete sawed/slotted like a control/expansion joint so that your water is directed away from where its currently pooling?

rons · Oct 6, 2023

figak said:
Has anyone here had experience with metallic epoxy floors, either in residential or commercial settings? I would love to hear about your personal experiences, tips, and any advice you might have. Are there specific things I should consider before making a decision?

I don't have experience metallic colors. But a thing to think about is how easy/hard is it to touch up compared with a solid color?
Face it, floors get scratched. Nobody wants to drop wrenches and other tools. But low probability events happen.

Joe Gwinn · Oct 7, 2023

I had the floor of my basement shop painted for exactly the OP's reasons, but it didn't work, for an annoying reason. The top layer of concrete didn't have enough Portland Cement in it, and so it dusts where-ever I stand and work, and the paint is soon worn away there.

dian · Oct 8, 2023

whether metallic or not this is a poured layer several mm thick.

1. prepare concrete with phosphoric or grinding (rent a machine) which is far better.

2. apply base coat/primer epoxy 2-3 times. especially grinding will expose thousands of cracks and you will have bubbles all over the place if you dont do it right (i would do 3 coats).

3) you need at least 3 people to pour the floor, especially if you have never done it.

4) most systems will change colour if exposed to uv, like near the door (→top coat/sealer)

5) you can add fine quarz sand to it for an anti-slip effect.

such floors are really decorative only. for a heavy duty application use a quarz filled system. its thicker and more expensive.

Mark Rand · Oct 8, 2023

Joe Gwinn said:
I had the floor of my basement shop painted for exactly the OP's reasons, but it didn't work, for an annoying reason. The top layer of concrete didn't have enough Portland Cement in it, and so it dusts where-ever I stand and work, and the paint is soon worn away there.

Stabilise the concrete with a commercial sodium silicate or lithium silicate product before painting. The concrete for my workshop had extra sand and water added at the plant while the second truck was waiting for pump truck to pour the first load, resulting in a lousy, weak, mix. I could/should have demanded that the supplier remove the bad concrete and re-pour the floor (which they would have done). But I was so exhausted by the whole build project that I let it go. Quite a while later, I treated the floor with lithium silicate. Stops the dusting and wear completely.

CalG · Oct 8, 2023

Thinset is a very useful material for "patching" surface defects in concrete.

Easy to get, no special requirements.

Joe Gwinn · Oct 8, 2023

Mark Rand said:
Stabilise the concrete with a commercial sodium silicate or lithium silicate product before painting. The concrete for my workshop had extra sand and water added at the plant while the second truck was waiting for pump truck to pour the first load, resulting in a lousy, weak, mix. I could/should have demanded that the supplier remove the bad concrete and re-pour the floor (which they would have done). But I was so exhausted by the whole build project that I let it go. Quite a while later, I treated the floor with lithium silicate. Stops the dusting and wear completely.

Lithium Silicate? That's a new one for me. I'll look into it. I had heard of Sodium Silicate. Thanks.

Though it may be too late in places as they have become oily due to messy neighbors of iron constitution.

rons · Oct 8, 2023

Several different grocery stores like Trader Joes and Ranch Market don't care about painted floors anymore.
They use a clear coat and that's it. Doesn't look so good if you always walk with your head facing down at 45 degrees or more.
After 45 degrees you have much greater problems than looking at the ugly floor.

A machinist guy once told me his dream:
Finish every project in the place and then get everything cleaned up and paint the floor.
Next day open the door to the shop and look at everything and smile.
Never told me what comes after that.

dian · Oct 9, 2023

Mark Rand said:
Stabilise the concrete with a commercial sodium silicate or lithium silicate product before painting. The concrete for my workshop had extra sand and water added at the plant while the second truck was waiting for pump truck to pour the first load, resulting in a lousy, weak, mix. I could/should have demanded that the supplier remove the bad concrete and re-pour the floor (which they would have done). But I was so exhausted by the whole build project that I let it go. Quite a while later, I treated the floor with lithium silicate. Stops the dusting and wear completely.

sodium silicate is waterglas. commercial? its cheap. however, as far as i understand, the surface doesnt lend itself to further painting/coating. do you have a different experience?

Greg Menke · Oct 9, 2023

Joe Gwinn said:
I had the floor of my basement shop painted for exactly the OP's reasons, but it didn't work, for an annoying reason. The top layer of concrete didn't have enough Portland Cement in it, and so it dusts where-ever I stand and work, and the paint is soon worn away there.

Our basement and garage floors are the same, sandy 1920's concrete. I mostly gave up on prep, just patching sometimes and covering with outdoor carpet and horse stall mats.

Fixing/leveling concrete floors prior to epoxy?

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