Finally getting a concrete workshop floor

For 20 years I've been waiting for all the planets to align and allow me to put a concrete floor in my barn... 6" thick, 1/2" rebar on 18" centers, 15 mil vapor barrier. I want to be able to drive any machine inside that will fit through the door!

The pour for the 1st stage starts bright & early tomorrow morning

It would have been a lot simpler to make the slab before the barn. Kind of like putting your underwear on after your pants. But the building was already up when I bought this place... and I have so much junk, and no place to store it, that it was simplest to do the center first. A new slab and 40x60 shop just isn't in the budget and I have waited long enough.
My four-post lift has been in the crate for several years now. You can see it off to the left side.

Next step is to move all the junk onto the slab once it's cured, then do the same prep on the full-length narrow strip and the other square section.

Have you thought about putting a covered out let under your lift this would be a good time to put conduit and a plug under it.

You'll be impressed with how much heat the concrete gives off while curing.
Leave some windows & doors open, and run a fan too, if at all possible, to move the moisture.

Good for you, I see too many people opting for a 4" (3 5/8") slab to save a couple of bucks in material then later regretting it.

The longest journey begins with a single step, enjoy the trip on finishing your shop
I went through a similar process on my pole barn to make it into my shop

Yep... compared to the cost of labor, a few hundred extra for a true 6 inches of 4000 psi concrete is well worth it. Tractors and a backhoe will be driven on it (not on the 4-post lift, just the floor!)

Phase One complete! Now it has to cure for a while so we can start on the six foot strip to the right. Since my friend doing the prep wants to do as much as possible with his 'hoe, waiting a while is prudent. Either that, or we have to hand-dig the dirt in sticky southern Missouri heat...

Cool. About 1/3 of my pole barb is finished and has a cement floor, the other half of it is still gravel. Before I ever did a floor in there I'd probably pour a slab outside first to have some more space to work on stuff without having to pull stuff in and out. Of course that will probably lead to wanting to put a roof over it and if there's a roof it's not much more work to wall it in....

Good job on the rebar on stands! Too many get cheap and don't use stands or even worse use chicken wire not realizing the weight of the concrete will sink it to the bottom and defeat the purpose. I always pay a little more and have them add extra cement to mix. Makes for a stronger floor or driveway.

Any thoughts on epoxy coating the floor? It'll never be easier to prep than when it's new and clean...

I can get this at Home Depot although it is likely to take two orders, after reading the reviews.
https://www.homedepot.com/p/Rust-Ol...ndustrial-Floor-Coating-322759/302690075

Looking good, Doc. Garage journal is probably your best resource for floor coating research.

Here's a youtuber I follow that applied that to his existing shop floor recently. https://www.youtube.com/watch?v=75NrKtnqjHA

This is the first of 3 episodes. The first vid is mostly prep work but does start applying the product starting around the last 4 minutes of the vid.

Good luck with the project!

I thought you were talking about a magazine at first... but that would not be anywhere near the oddest

Anyhow I've been browsing that forum and it looks like Armorpoxy would be a better choice than anything from a box store. Their"Job on a Pallet" with everything needed is $1500, but Garage Journal forum members get a 15% discount. Guess the price of the man-cave just went up a bit more

I did one of mine 14 years ago with plain rustoleum epoxy shield, it has been flawless. I waited 28 days, etched with muratic acid, and rolled it on. I am sure any brand is good but have had friends buy the high dollar cool guy coatings, and super clearcoats and they have problems with hot tires sticking to it. I will warn you that my paint will burn from weld slag, will come off if you beat on it with a hammer, will lift if you put lacquer thinner on it overnight, but that should be obvious. I have another shop with plain power honed super smooth concrete and I like it too, it has stains but as long as you wipe stuff up it is no problem either. I did not put plastic under that slab, 21 and did not know any better, so no faith the paint would stick. My painted floor was power honed, but not as smooth as my non painted. If yours is super smooth have someone shotblast it. The paint is slick when wet, I put rustoleum silica in at 1/2 the recommended amount for a little grip. If you overdo the silica it becomes a [censored] to clean. I think my next floor will be medium honed and concrete stained that brown rust color.
.

If you're going to be driving equipment in there and doing heavy work I wouldn't spend $1500 on coating. Have the concrete polished and then just put a coat of wax on it. You'll need to redo the wax every other year or so but it will hold up pretty well and it is easy to sweep up.

Interesting suggestion, thanks. But what happens when oil, gas or solvents inevitably drip on the wax? It'll pretty much instantly dissolve (and likely stain the concrete permanently).

A polished floor with wax on it will clean up pretty easily. If the concrete isn't polished then it will stain very quickly. When I worked at Xerox we had our machine shop areas polished and waxed. It was the best floor system that we ever came up with. This was in a machine shop where it was common to spill lubricant and other chemicals. Having the floors polished was the key. Grind and seal is a little less money than polishing. Call a local contractor and get some quotes.

Concrete densifier is well worth a look, and will noticeably help the durability of the slab + will help reduce dust produced by the slab.

Never heard of this stuff before, can it be used on cured concrete?

There are probably different types out there, but the type I used is applied to a cured slab.

These are all good.

https://www.legacyindustrial.net/products/densifiers/

It's used in alot of different ways. Sometimes applied before the slab is put to to work. Other times between stages of grinding and polishing.

It's well worth it, even if you change your mind and apply a coating later....but it prevents spills of all kinds from soaking in.

If you do a coating later on....and the coating ever fails you won't have dust and so on. If the slab has to be ground first before applying the coating, the densifier will give a nicer substrate.

I couldn't think of a reason to not use densifier, other than a slight expense. It's super easy to apply.

PPG high solids epoxy in gloss white is $87 per gallon, chemical resistant and does not tear up like most other paints. Tim

I decided to skip the floor coating. After many delays, finally the slab is finished, and I'm putting the lift together.
The decks (especially the one with the hydraulic cylinder) were too heavy even for two people to lift and carry, so we used a cherry picker.
Now I just have to fasten the cables to the ram and mount the power unit!

Looking good so far.

Floor and aprons finished, lift together and working I finally got to use the lift, but not for repairing my Dart or other vehicles... The next several days are calling for high winds, rain and possibly quarter-sized hail so I put the cars (that haven't already been hailed on) in the shop and on the lift. The last hailstorm that did $5000 damage to a '14 Impala didn't faze my '93 F-250 at all, other than breaking one marker light!

The truss that goes over the center of the lift needs to be redesigned to be a foot higher. Otherwise I can't put the lift all the way up and stand upright. But it will be great to be able to work on my cars without jacks, stands, and lying on the ground.
No more

The Dart is already safe in the attached garage where it resides when not making tire smoke

nice!

I would at least put a sealer on that concrete. Concrete never stops giving off dust. The sealer will eliminate that and also, if you spill oil or anything like that, it will prevent it from soaking in.

True. At one of the power plants I worked at all the electronic control systems were in a room with a concrete floor. It dusted so bad from just foot traffic that the filters on the cooling fans for the equipment were plugging. After about five years of fighting this (new unit) we put some kind of sealer on the floor that took care of the problem.

Nice work.

Densifier would be a good idea.
It soaks in and stops the dust, and you can't tell the floor has been coated/there is no visible coating.
Grinding metal, welding metal, fire, sparks, dropping heavy objects on it has no effect.
It also prevents future fluids from soaking in.

It's typically used before grinding and polishing concrete but can also just be sprayed on and left alone.

https://www.legacyindustrial.net/products/densifiers/hd37-densifier-plus.html

I used the above, started to move in and then won a contest for $500 worth of floor coating for free on garagejournal, so I
had to move back out again to apply the coating. Years later I've damaged the floor coating just as predicted
but both it and the densifier have done their job/no complaints.

I looked into that a few months ago while waiting for the concrete guy to pour the final section of the slab. Good sealers are expensive (at least $1k even for just 30x40) and need floor prep too. Cheap ones peel, lift and discolor and need to be removed, then reprep, then do it over.

Foot traffic will be minimal - just me when I'm working on one of my cars. I don't care if there are some oil-colored patches on the concrete

Besides, all my stuff is in the shop now and I really don't feel like moving everything from one side to the other (again)!

Finally, there is always dust coming in around and under the sliding barn doors, which face east and west, matching the prevailing winds. I'll never get it hermetically sealed... So I will just blow the dust away with compressed air, a push broom or a shop vac. I already learned that I can't paint worth a crap, so dust isn't a consideration there.

I am ready to start USING the lift and smooth dry floor

Interesting, never heard of that stuff. It would take 3 gallons to do my floor (one 6x40 section was hand-troweled, the remainder power-troweled) so that's $500 right there. I don't remember if it's 3500 or 4000 psi concrete but it's plenty strong and smooth as it is. I could buy a gallon and do the area around and under the lift, and see how that works out

I looked at the application instructions and am having trouble understanding the following:

"Avoid overlapping wet to dry as this can cause water spotting because the product will not be able to penetrate a dry area that was treated as well as in an area that has been treated but not yet dried."

What does this mean? How do you avoid a wet/dry interface as you move across the floor?

I read it as do not go back over an area that has already been sprayed and has since dried or spotting could occur.
I'd start on one end and finish on the other where you can exit. Don't end up back where you began.

It should be a nice garage when it's all done

Ahhhhh. Once you start, just keep going until you are done. Got it.

I agree. would never coat a shop floor again. Did it twice. Giant automotive suppliers polish their factory floors. Looks great and you can have it done again in high traffic areas.,

Even grocery stores are polishing concrete floors these days. Insanely expensive. At Kenworth Truck Co we spent over $100k just polishing the main walkway aisles. I thought it was an incredible waste, but the factory is a showpiece for tours, so it’s justified,

There are different levels of polishing. When I looked into it I found it was 50% more than Epoxy for POLISHED. All epoxy fails eventually. The biggest problem I've found with my Epoxy floors is moisture underneath causing issues. No way around that f there ANY moisture in the area. Polished floors "breathe" and don't have moisture problems. The air may have a moisture problem but not the floors.

We were looking at having a building built. I would DEMAND a water barrier (just thick plastic) under a concrete floor. Tough lesson to learn.

I had 15 mil vapor barrier installed. Well worth the few hundred for the big roll of yellow plastic! That area is definitely damp including all the water that comes off a 30x40 roof. Might want to add gutters someday

There is also rebar throughout, not just near the feet of the lift... I want to drive anything and everything in there that'll fit through the door, including my friend's backhoe, without worrying if the slab is strong enough. It's a minimum of 6" 4000 psi mix. That should be sufficient

On the subject of polishing, if you wax the floor how do you keep gas, oil, solvents from dissolving the wax?