How long to clean/grind floor?

[misterfixit]

I'm getting to the point I'm ready to work on my floor. I have a 1200 ft2 detached shop. I have a new (less than a year) slab I have built on. I have paint and spray foam overspray on it. I'm wondering about renting a floor prep tool and buffer from Home Depot to strip it all down to bare concrete. How long will that take? Has anyone done this?

 

[SolarColumbia]

Are you prepping for a coating or just wanting to clean it?

 

[nadogail]

That is almost like asking "How many hotcakes will it take to cover a Dog House"

 

[misterfixit]

Are you prepping for a coating or just wanting to clean it?

That is almost like asking "How many hotcakes will it take to cover a Dog House"

No offense but im not sure how much more information you could want. Like i said in my original post:
I have a concrete slab that is about a year old
It has paint and spray foam overspray on it
I want to take it down to bare concrete, meaning get all the paint and overspray off of it.
I'm looking at renting a floor tool from home depot to accomplish this.

since this is a rental, and they will want to know how long I will need the equipment, How long will it take to clean, strip, whatever you want to call it the paint and foam and get it to just bare concrete. How much time will I have to plan for? is this something i can do one afternoon, or is this an all day project.

 

[SolarColumbia]

If you're just cleaning it off you could get done in a day with a grinder. Just grind the areas that have paint, etc until they are clean. If you are grinding to coat it you should plan a couple of days as you'll want to have the rough concrete surface profile for the coating to adhere properly.

 

[benwah]

Gosh, this would be a perfect "honed concrete" job. Unfortunately I do not believe Home Depot has polishing accessories for their 10" Edco setup. Usually they only rent out metal bond diamonds from what I have seen, but it may be worth asking..

If you're serious about grinding it would probably take 2 days. Not sure how many sq ft/hour you can get with their tool. All depends on the hardness of your concrete and what tooling they have available. You will absolutely need to rent a vacuum with around 250CFM, and will absolutely need to purchase a 3M half face respirator (or similar). Any type of dust mask will not suffice.

Keep in mind, once you grind, your floor will be porous and open, and will have a very uneven finished look. It would be best to coat/seal it at that time, rather than leave it like that, IMO. Being left open it will readily accept any liquid contamination spilled onto the floor for life.

You may be able to get by just renting their 17" polisher/buffer and a stiff bristle nylon attachment to scrub the topical contaminants off to be honest.

 

[Killer95Stang]

I did 400 sq ft with a 7" grinder w/ diamond cup, dust shroud and shop vac. It took me 2-1/2 hours. So with a walk behind grinder, I can't see it taking more than 6 to 8 hours. I'd watch a few videos on Youtube. Some break down how much time per square foot.

Some of the businesses doing full flake polysparics will grind, basecoat and clearcoat in a single day in my area.

 

[LegacyIndustrial]

I did 400 sq ft with a 7" grinder w/ diamond cup, dust shroud and shop vac. It took me 2-1/2 hours. So with a walk behind grinder, I can't see it taking more than 6 to 8 hours. I'd watch a few videos on Youtube. Some break down how much time per square foot.

Some of the businesses doing full flake polysparics will grind, basecoat and clearcoat in a single day in my area.

The more you spend on rental equipment, the faster and easier it goes.


Sent from my iPhone using Garage Journal

 

[danski0224]

Gosh, this would be a perfect "honed concrete" job. Unfortunately I do not believe Home Depot has polishing accessories for their 10" Edco setup. Usually they only rent out metal bond diamonds from what I have seen, but it may be worth asking..

If you're serious about grinding it would probably take 2 days. Not sure how many sq ft/hour you can get with their tool. All depends on the hardness of your concrete and what tooling they have available. You will absolutely need to rent a vacuum with around 250CFM, and will absolutely need to purchase a 3M half face respirator (or similar). Any type of dust mask will not suffice.

Keep in mind, once you grind, your floor will be porous and open, and will have a very uneven finished look. It would be best to coat/seal it at that time, rather than leave it like that, IMO. Being left open it will readily accept any liquid contamination spilled onto the floor for life.

There is a crew of professional epoxy floor finishers working on a job that I am on, and I bet that it would take at least a week for a novice to do the floor prep steps that they are doing. Looks like a grinding step and some sort of shot blasting step. The equipment is at least 240V and it may even be 3 phase.

I have seen 480V grinders on other jobs.

This contractor on this job offers a 5 year commercial warranty on their product.

And absolutely yes on a properly fitting respirator.

And yes, finishing would need to be done right away.

It is taking them a month to do the process start to finish.

You may be able to get by just renting their 17" polisher/buffer and a stiff bristle nylon attachment to scrub the topical contaminants off to be honest.

If the floor is smooth, a 4" wide hand scraping knife on a pole would be the hot ticket.

 

[misterfixit]

Thanks for the comments. I'm not sure if I'm saying the right things, not sure on terms I should be using. What I want to do is clean my slab down to bare concrete. If I sand and or grind it a bit that's fine, but I don't need to. My plan is to use Ghost Shield densifier and then maybe a glass coat sealer.

I'm the one doing all the work on the building, I'm the general contractor and laborer. When we did the spray foam, the installer didn't have enough tarps to cover 100% of the floor. We covered most but obviously not all. Then after the foam was done, when it was time to paint, I was in a hurry and since I already had some foam overspray I didn't cover the floor when painting. Now, those are the things I need to get off to take it back to bare concrete.

This is what I have:

That's not dust around the corner area, it's the foam overspray.

I have used a floor scraper and it does take off a bit of the residue. But it leaves it still on the floor, in other words it reduces the thickness but doesn't remove it completely. I have also tried a power washer. That also doesn't remove it.

 

[toolin' around]

Sounds like you are not wanting to take a layer off the concrete, but just clean the surface contaminants off...

Try a small area with a 4” angle grinder using a nylon pad (they are a bit more aggressive than a scotchbrite pad, but similar)... this will help determine how easy/difficult it is to remove the spray.

I think HD has a similar pad for their floor prepper, or you may be able to to buy online just the pad to fit their machine.

Sounds like you have some areas requiring more work than others, so it’s tough for anyone else to estimate time... if the foam etc comes of fairly easily, it may be an easy day’s work... if not, maybe more... or you may just need to spot around some edges and tougher areas with a 7” grinder to finish.

 

[misterfixit]

Sounds like you are not wanting to take a layer off the concrete, but just clean the surface contaminants off...

Try a small area with a 4” angle grinder using a nylon pad (they are a bit more aggressive than a scotchbrite pad, but similar)... this will help determine how easy/difficult it is to remove the spray.

I think HD has a similar pad for their floor prepper, or you may be able to to buy online just the pad to fit their machine.

Sounds like you have some areas requiring more work than others, so it’s tough for anyone else to estimate time... if the foam etc comes of fairly easily, it may be an easy day’s work... if not, maybe more... or you may just need to spot around some edges and tougher areas with a 7” grinder to finish.

Well, I talked to the rental guy at Home Depot. He told me that the pads won't take off the paint and foam. He then told me that the Diamabrush tools will leave the floor scratched up and not looking good at all. he said not to use them if I wasn't going to put epoxy over it.

Anybody got pics of what the concrete looks like after the prep tool from Diamabrush?

 

[misterfixit]

Gosh, this would be a perfect "honed concrete" job. Unfortunately I do not believe Home Depot has polishing accessories for their 10" Edco setup. Usually they only rent out metal bond diamonds from what I have seen, but it may be worth asking..

You may be able to get by just renting their 17" polisher/buffer and a stiff bristle nylon attachment to scrub the topical contaminants off to be honest.

Well, update, I just got off the phone with another rental place. He suggested a buffer with 36 grit sandpaper and pads to take the 'stuff' off the concrete.

Word to the wise, Prevention really is worth a pound of cure. I wish I hadn't been so lackadaisical about protecting the floor during construction.

 

[benwah]

Well, update, I just got off the phone with another rental place. He suggested a buffer with 36 grit sandpaper and pads to take the 'stuff' off the concrete.



Word to the wise, Prevention really is worth a pound of cure. I wish I hadn't been so lackadaisical about protecting the floor during construction.

The problem with that is these guys are not taking the end product into consideration, they are only thinking about how to remove the paint and Spray Foam. 36 grit will scratch the hell out of your power trowel finish, your floor will never look the same again. I would suggest starting with some of the least aggressive steps and working your way up rather than starting very aggressively.

The least aggressive options in my opinion are a stiff nylon bristle under a floor buffer, a black pad under a floor buffer or a green pad under a floor buffer, all while the floor is saturated with water. Another person also mentioned a 4in scraper, this works great as well especially if it is very sharp and you have soaked the paint and foam in water.

 

[danski0224]

You'll never get the spray foam residue off (out) of the concrete. It will always be there, and it sealed off the pores where it landed, so it will show through a stain or light color or clear. The only way to remove it is mechanical abrasion once cured.

A 4" razor floor scraper will take it down to the surface of the concrete. Flooring installers use this tool all of the time.

Any type of operation where material is removed (grinding or sanding) will destroy your smooth existing floor surface and you will be stuck using a high solids epoxy.

As mentioned above, floor buffing pads are your only real option besides or in addition to the 4" scraper. Some of the buffing pads might be pretty aggressive, so choose wisely.

 

[misterfixit]

You'll never get the spray foam residue off (out) of the concrete. It will always be there, and it sealed off the pores where it landed, so it will show through a stain or light color or clear. The only way to remove it is mechanical abrasion once cured.

A 4" razor floor scraper will take it down to the surface of the concrete. Flooring installers use this tool all of the time.

Any type of operation where material is removed (grinding or sanding) will destroy your smooth existing floor surface and you will be stuck using a high solids epoxy.

As mentioned above, floor buffing pads are your only real option besides or in addition to the 4" scraper. Some of the buffing pads might be pretty aggressive, so choose wisely.

The problem with that is these guys are not taking the end product into consideration, they are only thinking about how to remove the paint and Spray Foam. 36 grit will scratch the hell out of your power trowel finish, your floor will never look the same again. I would suggest starting with some of the least aggressive steps and working your way up rather than starting very aggressively.

The least aggressive options in my opinion are a stiff nylon bristle under a floor buffer, a black pad under a floor buffer or a green pad under a floor buffer, all while the floor is saturated with water. Another person also mentioned a 4in scraper, this works great as well especially if it is very sharp and you have soaked the paint and foam in water.

Well, looks like the decision has been made for me. My original plan was to try to make the floor 'look nice', specifically to densify to help reduce dust and some gloss coat sealer type to make it pretty. Doesn't look like that is going to happen now.

So the fact is I screwed up by not protecting the floor during construction. My eagerness to get things done, and my misinformation of believing I could clean it later.....here we are. Short of much more money than I had planned and more time than I really have, I'm not going to do anything to the floor. My budget is totally shot at this point, construction materials really got out of hand in the middle of this. I might run my hand powered scraper over it, but it is what it is now.

Thank you all for the suggestions and ideas, I do appreciate them even if I can't use them.

 

[Armorpoxy]

When ready rent a Diamabrush on a buffer from Home Depot...they are inexpensive and will work well to prep lightly.

 

[WisJim]

I'm in the same situation due to overspray and am using the 4" scrapers from Ace hardware. I'm finding that water with detergent sitting on it awhile seems to help, but it still is a lot more work than a good job of covering the floor would have been.

 

[Mechtech]

For paint/foam overspray I would first try spraying a small area with simple green solution, let it sit for a while and then use a stiff bristle brush/buffer pad to see if it comes off. I was part of a crew in the Air Force that cleaned an entire hanger floor this way after the painters covered everything in overspray. Took a few days and some spots needed two or three passes but it worked.

 

[PoorUB]

You might be surprised what you can do with water, some degreaser like Simple Green and a 17" floor buffer with a nylon-grit brush. it would be an all day project, but I would bet you would get 90% of it off.

Speaking from experience!