How to level a floor>>>

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Hello all,

When my shop was built the contractor had a problem with the concrete and it started setting before he got a good finish on it. The end result for me is a floor that is not so smooth. I really didn't mind that because it is non slip...which I like after pulling my groin muscle several times in my old shop with a nice smooth floor covered in saw dust. Unfortunately I didn't realize until later when I started setting up machines that the floor is also not level...at all. It leans slightly to one side and is also about 1&1/2" low in the center.

Is there anything that can be done to solve this problem? Is there some kind of leveling compound that can be pouired in to cover the floor? Can another layer of concrete be poured on top of the floor?

Any suggestions would begreat,
Steve
 
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Trying to level a large uneven surface with levellers is expensive and time consuming. Plus your shop is out of commission longer. Add fresh concrete, I would make it more wet so that it self levels.
 
We had a basement floor that was a mess. Poor job also.

My Uncle a Mason advised Dad to use furring strips and plywood to fix the basement floor. We then laid tiles. Leveled that floor nicely and it was easy on the feet!

The alternative was to drill holes and make another pour. The holes were for rebar and attach grid and make a 3-4" pour.

The tile floor was a hit and easy sawdust clean-up!
 
You need a whole bunch of matchbooks for under all the legs! [:p]

Any way you do this is going to be expensive and time consuming.

If you pour a new floor over the old, you're going to want at least 2" minimum thickness on the high parts to keep it from cracking. There's also a liquid concrete bonder that helps bond new concrete to old, but it's a mess to use, and I'm not sure about its effectiveness. I've only used it on one job, and it was kind of a pain. New concrete and old concrete will not bond together on its own.

Building a sub-floor is going to be the best bet, and ideally, you'd use a pressure-treated 2x4 grid (laid flat on the 1 1/2" side) and shim up the boards on the low parts with small blocking. You can attach the 2x4s to the floor with countersunk Tapcons (or a .22 cal nail gun) to anchor it in place. Then pour concrete in the areas under and around the 2x4 gridwork to make it nice and solid so you can attach pressure treated plywood to it and finish as desired.

I'd also highly recommend putting down at least a 6 mil plastic sheeting vapor barrier over the whole floor under the framework. Moisture will wick up through the existing floor into the new concrete and wood floor, and the water in the new concrete needs to stay trapped in there as long as possible to get the best (hardest) cure. If the existing floor is as porous as you say, it'll leach away the moisture and cause cracking. Concrete isn't supposed to 'dry', it's supposed to 'cure', staying as moist as possible for as long as possible.

There's also a product called poly plate, or mirror drain, or waffle board that is really great in situations like yours. Basically it's a thin poly material that looks like a waffle laid on the floor. The dimples in it allow the new concrete to flow down and make contact with the floor, but on the underside, the channels between the dimples allow air and moisture to flow under the new floor, keeping it ventilated and dry.

It's a really good idea to clean the existing floor really well to get rid of all the sawdust and organic material to keep mold from finding food and thriving between the layers of concrete. I'd then apply a good concrete sealer before the plastic vapor barrier.

Also, if your floor is hydrogapped (there would be a 3/4" gap all around the floor next to the walls), you'll want to preserve that gap. although it's not a true drain system, it still helps to allow moisture to travel around the floor instead of over it at least in small amounts. It also allows the area under the floor to 'breathe'.

Is there at least a sump pit somewhere in the basement, preferably with a pump in it already? You'll want to keep that location in mind when you're building the new floor, too. Make sure that standing water can flow freely towards it.

Hope this helps, I'm kind of thinking on the fly. I was a foreman at a foundation waterproofing company for a couple of years, so I've got a good bit of experience dealing with weird basement situations. Feel free to email me if you have any questions that I can help with.
 
Hey everyone,

Thanks for all the excellent info!!

I am kinda leaning towards the pressure treated sub floor idea. That sounds a bit easier, cheaper and also sounds like it would be better on my degenerative discs and spinal stinossis!

Thanks again,
Steve
 
Everything that Karl said .... read every step of his post. That's what I did to my old patio three years ago ... before I turned it into my shop. A friend and I did it ... be ready for some back breaking labor. But it will be worth being on the level, so to speak.
 
Michael,
I had a house in Houston that did a Titanic on me... from the kitchen side on one end to the bedroom side on the far end of the house we had a 4" difference in the level... Du-West (not sure of spelling) quoted a mere $24,000 to tunnel under neath and jack it back level, or a alternative, pull all of brand new carpet and drill about 30 holes in the floor and pour concrete mix in to re-level for only $14,000.
It was cheaper to move.
 
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