# concrete floors in basement of new house are rough



## roomtogrow (Sep 26, 2012)

we bought a home with an unfinished basement that has failrly rough floors.  we'd like to stain the concrete; but, obviously, the first step is to determine how much of a task it'll be to smooth out the concrete.   some spots aren't so bad, and other spots have some lines that were left from when the concrete was poured.    how do i know how much i need to grind the floors down, or do i try to polish it first?  i've got 2100 sq. ft. of basement; is it feasible to do this job on my ownwith a rental grinder?


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## CallMeVilla (Sep 26, 2012)

There is a concrete grinder that looks like a large floor polisher.  It can do a very nice job flattening out those ridges and problems.  The task is dirty and challenging but you can do it yourself.  I would start with rough stones on the disk and then take it down to finer stones to get the best possible surface before staining.

Smoother is better.

I have done staining too.  You will acid wash the final surface but that will not fix seams or ridges.  Remember, the stain will puddle in those seams.

Good luck!


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## roomtogrow (Sep 28, 2012)

CallMeVilla said:
			
		

> There is a concrete grinder that looks like a large floor polisher.  It can do a very nice job flattening out those ridges and problems.  The task is dirty and challenging but you can do it yourself.  I would start with rough stones on the disk and then take it down to finer stones to get the best possible surface before staining.
> 
> Smoother is better.
> 
> ...



thanks for responding to my thread.   a couple more questions if you don't mind:

1) would you suggest trying to polish/sand the existing floor before going at it with a grinder? (obviously, you don't have the benefit of having seen the existing state of the floors; but, just wanted to know if that made sense to try that first.)

2) if i do have to grind the floors, is it likely that i will have to overlay the floor with a thin layer of concrete or self leveling concrete, or should i be able to polish with a fine grit sandpaper after grinding?

thanks for your help.


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## CallMeVilla (Sep 28, 2012)

OK, I would suggest light grinding and inspection first.  Lay a long level (8') on the floor to check for big dips.  Grind as needed to remove issues.  Think of this as if it was wood.  Coarse sanding first, followed by fine sanding last, right?  Same with the concrete.

If you pour new leveling concrete, I would do the whole floor, not just dips.  The variation in concrete finishes (self leveling is very smooth) may telegraph once you stain it.

I have seen trowel finish floors stained and they were just fine.  You do not have to have a polished floor before staining unless you are being VERY upscale with the basement.  For example, I did a patio which was troweled smooth in part and heavily weathered in the other section (pitted).  The troweled segment turned out looking really good  --  but the pitted segment gulped the stain and just could not compare.


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## Wuzzat? (Sep 28, 2012)

Never heard of it till now.

http://en.wikipedia.org/wiki/Self-leveling_concrete


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## nealtw (Sep 28, 2012)

Wuzzat: you've lived a sheltered life, it's been around for ever well a long time anyway.


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## BridgeMan (Sep 28, 2012)

To the OP,

Unless you are an experienced concrete finisher, you might want to consider paying someone to place a thin floor leveler over the 2100 S.F.  Trying to do it yourself with limited finishing skills is asking for (lots of) problems.


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## CallMeVilla (Sep 29, 2012)

Good advice BridgeMan  . . . You have to be systematic and meticulous in the back and forth and overlapping with a grinder.  We used a two man team - one to guide the grinder left and the other looped the power cord around the motor as a lassoo to pull the grinder back to the right.  We worked across every part of a 1800 sq ft area.

We vacuumed completely then checked for dips or bumps with the straight edge.  Bumps were reduced systematically.  In the end, the entire floor (which had been tiled with Mexican pavers and thinset) was within 1/8" tolerance throughout.  There was no need to fine polish.

I would say, if RoomtoGrow does not have the skills, hire a guy who does and work together.


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## Wuzzat? (Sep 29, 2012)

nealtw said:


> Wuzzat: you've lived a sheltered life, it's been around for ever well a long time anyway.


There are definitely gaps in what I know. . .I need to spend more time in HD and more reputable building material places.


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## BridgeMan (Sep 30, 2012)

Wuzzat? said:


> There are definitely gaps in what I know. . .I need to spend more time in HD and more reputable building material places.



Anyone who hopes to increase his/her DIY skills by "spending more time in HD" is using the wrong approach.  Learning things from people who wear orange aprons can be very risky, in terms of the depth of knowledge being shared.  Far better to spend some time observing (and asking questions of) the professionals actually performing the skills you wish to acquire.


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## Wuzzat? (Oct 1, 2012)

BridgeMan said:


> Learning things from people who wear orange aprons can be very risky,


It's worse than that.  
I ran into an auto mechanic years ago who had the most bizarre notion of how electricity works and yet he sort of made a living fixing cars.

I use these stores to see what's currently available because I tend, too much, to make my own stuff.  
'Cause *I'm cheap*!


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## slownsteady (Oct 1, 2012)

To the OP: Why do you want a concrete floor in the first place? Have you considered a different flooring material that might cover the rough floor without making all that dust & noise?


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## nealtw (Oct 1, 2012)

Our local HD has two guys that work in the same dept. One I have known for years from a different store and he knows his stuff. The other guy is just a waiste of lunch. The problem is the average diyer can't tell the difference.


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## CallMeVilla (Oct 1, 2012)

SlownSteady has a point.  You could cut your work dramatically with a different floor treatment.  Vapor barrier and laminate is easy  --  and trendy  --  and fast.  Unless the existing really sucks  . . . you could avoid all that mess by covering the mess and getting on with a beautiful finish job.

Well???????


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## nealtw (Oct 1, 2012)

Learning any of this in a small room like area that will be bathroom would be a good start then decide to go ahead with the plan if successful.


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## roomtogrow (Oct 2, 2012)

thanks for all the responses. 

i do prefer stained concrete just because I've had them before and because we have kids who track in lots of dirt.  we live in the South; so, the harsh winters and cold floors are not really a concern.

i'm probably going to take the advice of trying grind the concrete in a smaller room or bathroom to test my skills; then, if i'm successful, keep going - or, if not, put down a floating floor of some kind.

any suggestions on what size grinder? a local rental place has an electric walk behind 6 stone grinder that i can rent for $82 a day, or a 3 stone for $64 per day (understanding, of course, the grinding pads are not included - those are $7 or $8 each).


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## CallMeVilla (Oct 2, 2012)

Well, the bathroom is not practical for the floor polisher type grinder.  It will fly all over the place if you do not know how to handle it.  You are better off trying a small bedroom size area.  Trust me, these things can be horsey!

There is another model that is more stable, with a flat front on it.  More expensive to rent but might work.  Just do your homework before jumping in too fast.


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## roomtogrow (Dec 9, 2012)

so, I'm midway in the process of grinding with heavy grit stones (using a 6 stone grinder) my basement floors that appeared to have been rained on during the pouring process.  many of the rain impressions are so deep; I'm afraid I would have to expose the aggregate in order to grind them out.    the floors were so uneven that it would've been impossible to lay tile or very difficult to even lay hardwood.  so, if the staining doesn't work out, at least i'll have some smooth floors to work with.    i like taking on challenging projects; but, my gripe is with the builder - could he have not taken some measures to smsmooth out the concrete?


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## BridgeMan (Dec 9, 2012)

The floor pictures indicate that the concrete placement wasn't completely finished--just poured a bit stiff, struck off and hit with a few bull-float passes.  Contractor probably sent the boys home early to avoid paying them any overtime that day.

True "finishing" involves working the surface of the fresh concrete with floats, bringing up the fines (cement and sand particles) by repeated back-and-forth motions, to fill in the voids between all of the coarse aggregate particles.  Your floor's voids were never filled.  Meaning your contractor took advantage of the fact that you accepted the floor's condition when you first moved into the home.  Too late now, but you should have required the contractor do everything you're now doing, or install a nice tile floor over the mess he left (the open voids would make a great bonding surface for thin-set).  Either that, or hand you a check to cover the cost of having the work done by someone else.


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## nealtw (Dec 10, 2012)

Sure looks better.


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## roomtogrow (Jun 24, 2013)

Bridgeman, thanks for explaining what should've happened with the concrete pour.  Chalk it up to a lesson learned.   the builder said from the onset of the buying process that the basement was unfinished when he was finishing the house. Unfortunately, i did not ask the right questions...it would've help to have known that the pour was not "a stainable grade concrete."

UPDATE:  I've completed grinding of all the floors, and vacuumed up thoroughly.  I still need to vinyl patch up some deeper voids.  But, my question is if i have 1800 square feet that i want to overlay / skim coat, can i break that up into sections or rooms  by putting tape in the door like a threshold effect, or will the overlay perform better if i do the entire floor at once?

Is there a particular overlay material that performs best?  Any tips for mixing up that many batches at once?


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## BridgeMan (Jun 24, 2013)

A very skilled finisher could possibly put down 1800 S.F. of floor leveler, but it would be a very long day if it's done right.  I wouldn't recommend it if you haven't done a lot of concrete work (batching, placement, finishing) before, as the results might be unsatisfactory.  Breaking up the area into smaller portions would be the way to go.

It's been too many years since I last used floor levelers of any kind, and have only done so two or three times.  Meaning I'm not in a position to recommend a good one.  You should be able to Google it and come up with a few brands having decent performance reviews.


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## slownsteady (Jun 25, 2013)

Ok, so maybe it's my lack of knowledge at this point, but if you were going to lay down leveler anyway, why wouldn't you do it in the first place and save all that dust & sweat & cost??


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## roomtogrow (Jun 25, 2013)

slownsteady said:
			
		

> Ok, so maybe it's my lack of knowledge at this point, but if you were going to lay down leveler anyway, why wouldn't you do it in the first place and save all that dust & sweat & cost??



I'm definitely not the expert; but, here's my take. It rained on the concrete while it was being poured, apparently enough to cause the top layer to be really dusty.  It was also very pitted and uneven; so, it would've taken multiple skim coats to eliminate all the flaws.   I wanted to make sure the overlay would adhere properly to the existing concrete; so, i used a grinder to get up all the soft dusty top layer.  The grinder cost me less than $500 to rent (including supplies); so, i thought this would be more cost effective than multiple overlays.   Yes, it was hard work to grind down 1800 square feet; but, i think it was the right way to do it.


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## nealtw (Jun 25, 2013)

If mudmixer dosn't show up here, send him a PM.


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