Newbie question - Uneven concrete subfloor.

I recently moved into a second story condo and have encountered what might be a serious problem. When I was looking at the condo, I noticed a gradual dip in the middle of the carpeted living room (approximately 10' X 10' and perhaps 1 inch deep at the center). We hired a building inspector to check it out and were told that the plywood floorboards were slipping due to settling, though the condo was structurally sound. He also said that this could easily be fixed at a minimal cost by pulling back the plywood and reinforcing the frame with some 4X4's. Well, today I peeled back the carpet to take a look and discovered that the subfloor isn't plywood, it's concrete! What the ?!?
Anyways, the condo is about 20 years old and the previous owners assured me that the dip hasn't increased in the past 6 years or so. Assuming that the frame is in decent shape, what would be the best (and most economical) way of leveling the floor? I only plan on living here for another 3-5 years and don't want to spend too much in improvements. At the same time, I'd hate for my floor to collapse onto my neighbors downstairs. Any advice? Thank you in advance.
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.

So much for the quality of the builing inspector. Try to get your money back as he is a fraud.

There are concrete compounds that are for floor leveling. You'd have to remove the carpet and spread the cement and finish it off. You may want to talk to a pro for a job like that.
It may be best to determine if the floor has sagged over the years or if it was not properly finished when the place was built. The fact that there is a dip does not mean it is a structural problem. Any cracks? It could well go back to the original builder.
--
Ed
http://pages.cthome.net/edhome/



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Edwin Pawlowski wrote:

Hi, Did Sumo wrestler live there, LOL. Leveling is not a hard fix unless
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You have a fairly simple one to fix. You need some floor stone. Here come the choices: gypsum based / cement based / self leveling
I prefer cement based products as they are not affected by water and there are no incompatibilities with adhesives.
There are several manufacturers. Here is a good one: http://www.mapei.com/MapeiAmericas/en/products_line3.htm
(top posted for your convenience) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Keep the whole world singing . . . . DanG (remove the sevens) snipped-for-privacy@7cox.net

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In a condo its possible that the slip forming was removed prematurely. An inch dip over ten feet could also be the result of "a tired finisher". If there are no cracks i suggest you go and find something else to worry about--try global warming or killer bees.
-- Troweller^nospam^@canada.com
Remove the obvious to reply. Experienced and reliable Concrete Finishing and Synthetic Stucco application in the GTA.

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Roll back the area, no cracks?? Then no problems!
Self leveling concrete is pretty easy to use but its not cheap! (bags are around 30.00)
What I did was to clean the area, then use a latex primer to prep the self leveling concrete a good surface to bond to.
Next mix up the batch, poor it on and spread it out. The the most important step, LEAVE IT ALONE. Its going to level itself before it sets up.
Make sure the whole process is done QUICKLY, this stuff likes to setup pretty fast. It can make a nice clean flat surface.
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Was the concrete cracked? Anything opening up voids in it?
Probably not, as it was built that way. There might even be a drain in the center of the room if it was built that way. The space you "bought" might have originally been something other than an apartment; do you know anything bout the history of the building?
Watch out: Before you do anything to "fix" that, be certain the condo rules & regs don't forbid it, or you could get in to some pretty hot water. You're getting some pretty strange advice for a condo. You own a condo, but you can't necessarily do anything you want to or with it. Check your papers carefulyy.
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Are you sure that whole floor is concrete? May be the floor was wood framed and someone put some leveling compound over the top in an attempt to fix the problem? This means the concrete that you saw may be the leveling compound. Does the floor sound hollow when you walked over it? If yours is really a concrete floor, you can use leveling compound to level the floor. Although leveling compound is expensive, you should not need that many bags for a 10'x10' area.
Please beware that leveling compound only has limited self-leveling capability. You cannot pour it on the floor and expect it to spread out on the floor all by itself. You need to help it alone using a straight edge or something. If the whole floor is basically level except for the middle of the floor, this job should be relatively easy to do for a DIYer. But if the whole floor is not level and if you really want to level it, you may be better off hiring a professional to do this. The reason is that the leveling compound is not forgiving. If you made a mistake and you wanted to undo your mistake, you will have a hard time removing the hardened leveling compound.
Have you paid a visit to the apartment right below yours to see if their ceiling is OK or not? At least to confirm that the problem has been stablized.
Jay Chan
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Hey fh!
Are there any cracks in the slab? If not, I would think you are probably ok. I am planning on glueing down pine on my concrete slab. My slab has some uneven spots that I need to level. The best bet is purchase some self-leveling mix. I plan on trying something called Henry Floor Smoother - a concrete type mix that you mix, pour and spread. You can find it at Lowe's
http://www.lowes.com/lowes/lkn?action=productDetail&productId831-41173-FPOSMT095073&pad=true
If that link doesn't work, just go to the Lowes site online, type in your zip code and do a search for the product.
Its not that difficult but can be messy if you don't prep right, but all the instructions will be with whatever product you use. It's pretty quick and easy stuff. However, if you are planning on keeping your carpet down, I wouldn't fool with it until you are seriously considering selling. Unless it's annoying you now. I don't know how much of it you have peeled back to see your slab, but pulling up the carpet and putting it back down snug can be a bit of a pain as well. Again, not too difficult, but a job in itself. It's probably a two weekend job. But it might be just as easy to have a flooring person come in and knock it out for your prior to you putting the condo on the market. Prior to him/her coming out, you could have already pulled up the carpet which would save you an hour or two of billable labor hours at 40-50 bucks an hour.
If you plan on putting wood down, you will have level it.
Hazen[
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Hey Hazen,
Thanks for your reply. I really appreciate your advice.
Is self leveling concrete and other similar products pretty easy to apply? I heard it can be pretty messy and risky if you're not careful. Again, thanks for your thoughts.
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Hey fh -
Self leveling is pretty easy stuff to work with. If you prep right, it won't be messy.
Keep in mind...NONE of this stuff is rocket science. And you CAN do it. Maybe not as fast but you can do it. Having said that, it also depends on the particular job. The real question is...do you really want to do it, or are you wanting to save yourself a buck. Like I said, if you are more interested in trying to save a buck, I'd probably have a floor/carpet guy/gal come out to do it. Fairly routine for them, they will have the right tools and they will knock it out rather fast and it probably wouldn't cost that much. But get an estimate, then price out the materials if you do it yourself and if the difference is significant, give it a shot! If not, let the pro do it.
If you really WANT to do it (I do enjoy doing this stuff, so it is not so much of a money saving thing for me. Sometimes smaller jobs, after you buy all the stuff you need, may not save you that much, so it becomes more of a fun project). Buy a video or book on flooring. They all have pix on how to put down self leveling concrete. It really is pretty routine. Mix it in the bucket to specific consistancy, pour out a small amount and trowel it smooth feathering the edges. Do all the prepwork before you get started. Goggles, gloves - rubber medical type, hat if your hair is long, knee pads, old clothes, 5 gallon painter's bucket, drill with a long mixer attachement, trowel and your mix. Pull up your carpet, roll it up, mark where you started. Run a string from one corner of the floor diagonal to the next. Find something like a cinderblock (or someone) to hold it down to the floor in one corner while you hold it down on the opposite corner. You will see the dip. Walk up to the point of the dip that is closest to you. Take the string in your hand (while the other end is still secured) pulling it taught and leaving it level to the ground. You should be holding the string down on the outer edge of the low spot. Then begin dragging the string across the low spot from left to right marking the perimeter of the low spot. Thus you will draw an outline around edge of the dip. I know this sounds like a pain, but this will take about 5 minutes. Once you outline the perimeter of your low spot. Mix your concrete, then pour the concrete in the center. Let if flow out naturally. Depending on the flowability, if it is a little thick, you may need to trowel it outwards from the center to your perimeter lines. Lightly drag the trowel from the top of any high spots pulling the concrete to the perimeter. Start out pouring less until you get a feel for the area, the viscosity of your mix, where the concrete flows, etc. You can always add more concrete. Keep in mind it should flow more than you will have to spread. But if not, no big deal, just spread with your trowel. Once it is smoothed out and level by the naked eye, and it begins to harden slightly, do your string test agian. It doesn't have to be perfect, but if its within about 1/4" to 1/8 of inch, you will be fine. Then walk away and let it dry. Once dry, roll the carpet back over and you are done. Now, I have never tightened carpet but again...it ain't rocket science. But read up on it first.
Remember, if you pour too much too soon, it may naturally spread beyond your perimeter lines so start out with a small amount. Let it flow naturally to test then use the trowel to spread. It may result in you spreading beyond your original lines. But that's ok.
Like I said, I enjoy some of this stuff. But, if the cost to have someone else to do it is within your budget, get someone to do it.
Let me know how it goes!
BTW, I hope this makes sense! It really is pretty routine. Especially since you have a specific low spot.
Hazen
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Whoa, what a reply. I can't thank you enough for your time and thoughtful responses.
Sounds like this project would be pretty hard to screw up. I'll let you know how it goes.
Cheers!
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Hey fh
One more thought. I would take a half day or so and research the construction supply places in your area. See if your more local, commercial type lumber/home supply place (not necessarily Home Depot or Lowe's) carry a more commercial grade leveler. Keep in mind the higher the viscosity of your mix (watery) the less durable. Easier to apply perhaps, but it may not be as durable in a high traffic situation. You should be fine with a carpet/carpet pad over the top, but I might errr towards a thicker mix and better product. I am not saying that the Home Depot/Lowe's type stuff is bad, it may be great, but do some research. Sometimes, when buying this type of product, paying a little more may be a good thing...And try and ask a nuetral source, not someone who stands to "make a sale" by boasting their product.
Also, you may need a type of etching primer to put down on the concrete slab before your pour the leveler. It's a matter of rolling it on with a paint roller. Like I said, the mix should naturally level out, and if it does, all you will need to do is trowel out the edges to try and create a smooth transition. Even if the product you purchase states No primer needed, do it anyway. Not that big of a deal and will help the mix bond to the slab.
take a look at this link for an idea...
http://www.custombuildingproducts.com/HowToTile/InteriorFloors/Uneven/Prep.aspx?user=diy&lang=en
Hazen
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