Refinishing Concrete Floors

Bob Borson —  December 3, 2012 — 34 Comments

Grinding and polishing my concrete floors technically started as an idea 4 years ago … then I thought I would do something about it myself 2 years ago by acid washing them (here).

That was a terrible idea and didn’t get me very far. Fast forward to the month of November 2012 and finally the dream was going to come true.

I thought …

I hoped …

I lost A LOT of sleep.

 

Concrete Grinding - Before 01

As a brief primer, my ENTIRE house has exposed concrete floors and with the careful placement of a rug here, a chair there, they look all right. And by “all right” I mean not very good. They were a swirly-twirly mess of different shades and stains. The original stain was put on using a penetrating sealer and mixed into the top coat of wax. This means that over the years, the areas that got mopped more became lighter in color, and the parts that were under rugs remained darker.

Since we had to clear out the house to deal with the concrete floors, you can see what I’m talking about in all the “before” pictures.

Ugh.

I was extremely nervous that I might be making a terrible mistake.

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Concrete Grinding - Before 02

Concrete Grinding - Before 03

In the picture above, on the left hand side you can see a patch job that was done on the concrete slab sometime in the past. You can also see where the newly poured slab meets the existing brown-stained concrete slab. Despite having conversations with the concrete contractor about trying to match the mix of the existing concrete, it was nearly impossible because the sand and aggregate would have to match precisely … which they wouldn’t. We might get it close but even with close you could count on the two slabs always looking slightly different.

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Concrete Grinding - Before 04

Here is a perfect shot to indicate the color variation between the floors. On the far left you have the concrete floors that were covered my rugs, the middle section was the main circulation path for the house and got “cleaned” the most frequently (meaning it had the most color removed.) On the far right you can see the new slab.

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Concrete Grinding - Before 05

Concrete Grinding - Before 06

This was the floor in the Master Bedroom under the carpet – a bit of a mess. So maybe now you can understand why I was so concerned about how the floors were going to turn out. It was because of this that I brought in FloorRescue about 90 days before work was to begin to do several test grinds so that we could see what might be expected once the floors were polished.

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Concrete Grinding - hand equipment

Concrete Grinding - testing hand equipment

Concrete Grinding - testing hand equipment

If you take a look at the grinding wheel in the picture above, without knowing anything you can see that it is a serious chunk of metal that will take off the top layer of concrete off (and the color along with it) in short order.

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Concrete Grinding - Before 07

It would take forever to grind 2,000 square feet of concrete down using small hand-held equipment so the plan was to bring in two HTC hooded floor grinders. Even then, the plan was to run two crews for 8-12 hours a day for 4 days.

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Concrete Grinding - hooded HTC's equipment

This is what the underside of one of these grinder looks like. All business my friends … and I’m told that these things weigh around 500 pounds and while that sounds a little generous to me, they are heavy. They need to be heavy so that the weight is pressing these discs down onto the concrete in order to grind away the top layer of concrete and aggregate.

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Concrete Grinding - the grinding begins

After the first day of grinding, this is what I found … not a whole lot of progress. They had put up some plastic to protect the walls and they had made the initial top coat of the concrete on the left hand side of the picture above.

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Concrete Grinding - end of day one

What I wasn’t prepared for was the amount of concrete dust that was E V E R Y W H E R E!!! Truth be told, the relatively clear photos you see above were taken around 11:30 at night after the workers had been gone for about 4 or 5 hours. What I walked in on (obviously right after they had called it a night) was in the next picture …

Concrete Grinding - the dust is unbelievable

Whoooo Wheee!! That is some serious cough-inducing, eye-reddening concrete dust … and believe me when I tell you that concrete dust is fine like baby powder and as a result there was a layer of it on everything. As a result, I decided to spend the next 4 hours of my evening covering everything I could with plastic.

Which included ….

Concrete Grinding - plastic protection for the fish tank

My daughter’s fish tank. We had set it up in the bathroom so that it could sit on the counter (all of her bedroom furniture had obviously been removed). I made a flap in the plastic out of blue tape so that I could open it up nightly and feed the fish.

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Concrete Grinding - the dust storm

Concrete Grinding

Progressed moved along at a slow but steady pace and the owner of FloorRescue had some concerns that they would not complete the project in the estimated 4 days. He wanted to make sure I understood that they wanted to do it right and the floors were taking a long time to grind all the color out. His solution was to have his guys simply work longer days but even then, it would probably take 6 days to complete the project.

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Concrete Grinding - late hours

Concrete Grinding - most of the color is removed

Here is a look at a section of the concrete floor after the color had been ground out. The more you grind, the more aggregate you will expose. As it turns out, our floors were nowhere near level, even over the span of a few inches. As a result, there is plenty of aggregate that was exposed in the floors which I kind of like – makes it look more like terrazzo.

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Concrete Grinding

Concrete Grinding

Concrete Grinding - the equipment

It took a lot of equipment on this job and this was just a small portion of what was used. This was a time-consuming, messy, labor intensive process and we haven’t even got beyond the grinding process. I’ll cover that in tomorrow’s “Part 2″ post – the cleverly titled “Polishing Concrete Floors.”

BOOM!!!

I just blew my own mind so I’ll leave you with one last final image in preparation of tomorrows post…

Concrete Grinding - concrete dust is like brown baby powder

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a dirty toilet…

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  • http://www.denafloors.com/ Noman

    Great job done and I also need to refinish my concrete flooring as soon as possible. Amazing post.

  • Frank Chappell

    I almost hate to say, but I kinda like the “concrete grinding – before 04″ photo. the different colors help define the spaces. Of course,the effect was unplanned, and the lines are uneven and I’m looking at it as someone who didn’t have to live with them. Viewing the other before photos, I agree with you that the whole floor needed a redo.

    • http://www.lifeofanarchitect.com Bob Borson

      Glad it came together for you because it’s to late to change now!

      Cheers

  • cheho

    This may sound naive, but why not pour a new batch of concrete over the old instead of this? Adhesion?

  • cheho

    Love this. I want to start a biz doing specialized concrete floors.

  • Joe K

    I tried this and it was a disaster.

  • James D

    Going through the grinding process now. Any tips on cleaning up all the dust that is left over?

    • http://www.lifeofanarchitect.com Bob Borson

      not really – it got EVERYWHERE!! If you were to cover and seal everything off with plastic that would certainly help. In the areas where we had plastic, the dust was reduced but it still found a way to get through somehow. Once we started cleaning up, we used shop vac’s with brush heads to suck up the dust. The process took a long time but eventually we got it all.

      Good luck!

      • James D

        Thanks Bob. Yeah, plastic went down but somehow made it’s way everywhere already.

  • Patrick

    Bob,

    I own a concrete restoration company in Austin. When we grind/polish concrete it is 95%dust free. The investment in the dust collection equipment was substantial, but well worth it. Just ask our customers! Five Star Finish

    • http://www.lifeofanarchitect.com Bob Borson

      Patrick,
      For all I know, this was 95% dust free as well, just depends on how much is the 5%

  • Kevin

    Just think of all the dust the workers are breathing.
    I’ve been polishing concrete for six years.
    I just started wet grinding and will never go back to dry.

    • http://www.lifeofanarchitect.com Bob Borson

      brutal – I can’t imagine.

      Originally I thought they were going to use the wet method but they decided not to for one reason or another.

  • Concrete Davey

    As a concrete repair contractor, I have some experience with these jobs. Dust control is the number one priority. Clean the filters, clean the filters, clean the filters. The vac filters must be kept clean. It’s a pain to stop so often to clean them and my crew hates it. Also set up a positive air system like in mold remediation. Vent, Vent, Vent. Constant air movement and constant filter cleaning.

    • http://www.lifeofanarchitect.com Bob Borson

      I think they followed that plan – I know when I popped in, I typically found ventilation fans blowing through open door and a few guys emptying out large canister vacuums.

  • Ken Thomson – Architect (UK)

    Great post Bob!
    I kinda like the colour you have ended up with, with all the exposed agregate, it looks like it could add a lot of light to the interior of your house.
    Looking forward to the next installment :-)

  • http://twitter.com/Secret_Design Secret Design Studio

    Bob, I have done a similar job in my family room, and like you I underestimated the amount of dust and mess it created. I discovered that no matter how well you think you have sealed up everything with plastic and tape, the fine dust will find a way through. Within a fortnight of finishing we had to replace all our TV, video and hi-fi equipment that was “sealed” up in another room due to dust damage. If that is a large wall-mounted TV to the left of your fireplace it will probably be too late to do anything to save it!

    • http://www.lifeofanarchitect.com Bob Borson

      yes – I did get dust everywhere but somehow I seemed to have dodged the destroyed electronics bullet. I wrapped all three of my TV’s (they are all wall mounted) and other than what I spilled on them while removing the plastic, they appear to be in fine shape.

  • http://www.facebook.com/francisco.garcia.127648 Francisco Garcia

    Bob, what’s the plan for the sawcut joints? I imagine there’s color inside them too?

    • http://www.lifeofanarchitect.com Bob Borson

      They used a hand held tool with a metal wheel on it called a crack-chaser. It removed about 98% of the color from the joints

      • http://www.facebook.com/francisco.garcia.127648 Francisco Garcia

        Cool. Sounds like they didn’t grow the joint either? I’m picturing a pizza cutter.

  • http://twitter.com/RigginsConst Riggins Construction

    Oh wow. We can’t wait to see the finish photos.

  • http://twitter.com/Alexandrafunfit Alexandra Williams

    You will be finding that dust on everything for years to come, I imagine.

  • Kat

    I hope you’re planning on getting your duct work cleaned after all of that!

    • http://www.lifeofanarchitect.com Bob Borson

      we shut the system down before the process began so we don’t have messy ducts. The amount of blowback after the fact has been almost non-existent.

  • architectrunnerguy

    This is one of those projects, where when it’s complete, you’re completely over the learning curve. Yet you will probably never have the chance to do or have it done again!

    • http://www.lifeofanarchitect.com Bob Borson

      I probably never will for my own house but now I am equipped with valuable first-hand knowledge to use this process on other projects

  • http://twitter.com/timraleigh timraleigh

    Great work in progress photo’s and documentation, thanks. Floor looks great but if it’s anything like red clay from Mexican tiles you will be finding dust in nooks and crannies for the next 6 months.

    • http://www.lifeofanarchitect.com Bob Borson

      Thanks Tim!
      Luckily (in this case) our house isn’t that large and before we moved back in, we cleaned out the inside of all the cabinets and drawers, vacuumed all the walls and ceilings, etc. for days before moving our belongings back into place.

  • Rose

    My boyfriend refinishes wood floors & they have to spend quite a bit of time hanging plastic like you did in the kitchen. The contractor should have done that as part of the bid and also warned you about the amount of dust.

    • http://www.lifeofanarchitect.com Bob Borson

      They did put up a fair amount of plastic and they did warn me that there would be dust – I think I might not a fully realized just how much there would be!

  • Paul Scharnett

    I think that toilet may have seen better days, Bob!

    • http://www.lifeofanarchitect.com Bob Borson

      there are so many potty jokes I could make …

      Imagine that level of concrete dust on everything, in everything, etc. I spent almost as much time cleaning up after the grinding as I did actually grinding the floors.