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drh 02-09-2008 04:36 PM

How to make a concrete floor smooth?
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Hi guys -

Wanted to poll the audience here - we just had a contractor finish pouring a new basement floor for us, and as it's drying, I'm seeing all sorts of trowel lines which doesn't seem right to me (see pictures below). My question is, how can trowel lines such as this be corrected (ie: blending into a smooth floor?)

Is this something that a floor grinder would need to be brought in for? Or are there self leveling smoothing/polishing compounds that can be poured over top? At the end of the day, I was hoping for a smooth concrete floor, and not one potted with trowel marks.

Any advice on how I can go about fixing this would be appreciated!

Chris Johnson 02-09-2008 04:43 PM

That floor is still curing, from the pictures I can't see if it is smooth or rough, once the floor cures it should lighten up a fair bit (Unless you have moisture trapped below it). When you say rough, is it rough like sandpaper (rocks sticking up, etc.) or are there lip marks from the edge of the trowel?

Grinding can be done, but I tell you, your wife will kill you when all that fine particle dust is everywhere in the house above, microtoppings work pretty good as well as a polymer floor leveller, but wait at least 28 days for that floor to cure/crack out before doing anything

drh 02-09-2008 05:01 PM

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Chris - thanks for the quick response.

The floor was poured yesterday, it is certainly still curing and since we have a radiant floor system beneath the floor with 3/4" insulation, I'm told it will cure longer than 30 days.

The problem I have is that the trowel marks have left visible bevels, lines that produce an uneven surface. I'm posting another picture shot straight down where you can see the uneven surface from the trowel. I'm certain that even after curing, the floor will not have a smooth consistency or look to it. When you walk on the surface, you can feel the trowel lines beneath your feet. This doesn't seem (or look) normal to me..

nap 02-09-2008 05:27 PM

Not a concrete guy here but that looks like crap. It does not look like he ever finish troweled it. Whatever you feel now is what you will feel when it is cured.

Chris Johnson; any chance of a wet grinder? I see them used on terrazzo whenever it is installed.
No dust:thumbup:

Chris Johnson 02-09-2008 07:47 PM

Okay, now I can see the job, it's a poor finish job, obviously the guy was rushed, wanted to get home and not finish the project properly, that is unacceptable. Funny thing is if the guy went and got a coffee and came back, finished his coffee it may have been the ideal time to finish it smooth.

Concrete is the hurry and wait game, hurry like hell to get it in and get it flat...wait for it to set so you can finish.

What are you planning for a floor finish? This will dictate how you handle the situation now, If tile the tile guy can float most of it without issue if it's what I see in the photo, Carpet and Laminates would need to flatten any edges and maybe float a little if necessary, Vinyl sheet goods...forget it...not gonna happen.

Assuming you have a retention, you have a bargaining chip in your pocket, but some discount is needed for work like that or they should repair it to an industry acceptable standard.

Wet grinder will work, no dust, but water everywhere, that's why you don't see this equipment being used in residential homes.

nap 02-09-2008 08:25 PM


Originally Posted by Chris Johnson (Post 96422)

Wet grinder will work, no dust, but water everywhere, that's why you don't see this equipment being used in residential homes.

:thumbup: I figured because it was in a basement that seemed to be totally empty it might be a reasonable idea.

Chris Johnson 02-09-2008 08:30 PM

You probably can use a wet grinder, it just not a common residential tool that's all, people get really excited when they see extreme water floating around their house, same goes for dust.

I will say this, those floors look really green still, I'm betting you can scrape the ridges off still at this point. you'll get the floor flat, not smooth, it'll be some what rough but if you're putting carpet down or laminate no one would notice the roughness.

drh 02-09-2008 08:34 PM

Chris - I appreciate the response - and this is exactly why I was turning to these forums for help, because it just doesn't look right to me in this state.

The guy laying the concrete was seriously sore after troweling for two hours when the pour initially went down. He did mention to me that he would return within 3 hours of the pour to finish smoothing -- but that didn't happen. Instead he returned the next day (this morning).

Is it too late for him to fix this? I absolutely do have a large portion of his payment still pending so the bargaining chip is most definitely in my corner. I'm just wondering how best to approach this - I was thinking perhaps asking him to provide a "skim coat" over the entire surface to smooth out the flaws? Or is that a measure that would have to be taken after the floor fully cures?

Regardless of what I'm putting down over the floor, I really don't like the way it looks, and to me, it's a principle thing whereby I paid for the work to be done, and I want the job be done properly. I'm just not sure what the options are at this point for him to finish this off properly and smooth out the floor?

The answer I got from him when I asked about the trowel marks was in line with "Well, that's the way it's probably going to have to stay" .. which really bothered me. It just struck me as the lazy man's response.

Perhaps the answer is no final payment until the floor is done to my satisfaction...

Chris Johnson 02-09-2008 08:59 PM

Well with that attitude of "Well, that's the way it's probably going to have to stay", I would say you need to have a heart to heart with the guy.

I have the attitude of "would I accept this on my own house", to answer that on your floor, NO, I wouldn't.

I get sore myself doing flat work, how big was the crew? Sore or not, there is no excuse for the poor job.

And in my opinion you are right, no final payment, but don't say until the floor is done to my satisfaction, say until it meets industry standards. I'm not picking on you here, but your satisfaction may be higher than industry standards and industry standards are the minimum a contractor must abide by.

I'll be the first to admit, I've 'lost' a floor before, I didn't make an excuse, I offered to redo it or carpet the basement for the people, they were more than happy with the carpet offer, cost me $ 600.00 to make the people happy. Well worth it in my mind compared to chipping out and repouring, and they themselves did not have to save up and carpet at a future date. I even got referrals from them.

Do me a favor, get a chisel (Dull or smooth, doesn't matter) (Hoping you have one in the garage) go down and using firm pressure try and 'cut' the ridges off the floor. Do a few feet, clean it up and see if that is acceptable to you. If the floor is still generating heat you have a good chance of doing this. If it is, get on the phone NOW with the contractor and tell him to get his ass over there if he wants to save the floor and make it acceptable to you. It could very well take him several hours to do this, but save both of you's the aggrivation of A) Redoing the floor B) Fighting before a judge

Sometimes the easiest thing to do is push the guy to get it done right and move on. You know who not to use in the future.

Bud Cline 02-09-2008 10:38 PM

Looks to me like the guy just simply ran out of steam. I suspect those are Darby marks making the ridges and swirls and they need to be addressed. The sooner (someone) gets on that floor with a large surface grinder the better. The guy that made that mess is the guy that needs to fix it. If he can't grind it then it may have to be capped with an SLC product - also at his expense.

Time is of the essence.:) The longer you wait the harder it is going to be to fix.

drh 02-09-2008 11:04 PM

Thanks to all for your responses, this has been extremely helpful. You're absolutely right, there is no excuse to leave the floor looking like this. When the contractor showed up early this morning, he admitted that he had fallen asleep the night before, but intended to get back to smooth things out originally. He obviously must know in his mind that this is a botched finish. I just can't imagine anyone would be able to look at this, think to themselves that the job is finished, and ask for final payment.

The worse part about the whole matter is that the concrete is covering an intricate layer of radiant in-floor PEX piping, smashing it out at this point would be an absolute disaster.

Unfortunately I do not have a chisel at hand, but I am going to phone the contractor tomorrow and have a heart to heart with him, let him know how things stand. The sooner the better.

drh 02-10-2008 09:43 AM

One quick followup question - if the contractor was to add a skim coat of finishing cement over the top of the existing pour, is this possible? Would a possible solution be to re-apply a thin coat of cement to smooth out the rough edges?

I'm concerned this may impact the ability of the cement below to properly dry...

Chris Johnson 02-10-2008 10:34 AM

Skim coating is possible, although difficult to do, perhaps a floor leveller would be better, using a rake to move it around and when done gives the floor a uniform look. If you have a floor drain the material is going to want to run towards it, plug it prior to applying the leveller.

Don't be concerned about the concrete below not drying...concrete does not 'dry', it 'cures' and it can cure under water believe it or not. Your slab will be cured to 75% +/- today (3 days) and be around 98% in 28 days, sometimes the cure is extended by adding mixtures to the mix, but for a floor in your basement I highly doubt any such thing happened as it is not required.

joasis 02-10-2008 12:59 PM

It is a shame to work like that done....and all because this guy lacked the experience or wore himself out troweling before the correct time. There is an adage about work it when it is ready, not when you are ready. This looks like he was too tired to work it when it was ready....

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