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concrete slab tolerance

Richie Rich

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Once again searching for information about a building here in texas.

I've been grinding on this concrete for quite a while and am curious as to current day tolerances in the slab. For example over an 8' are the float to approximate level was about 5/8". Grinding in about 6' square area exceeded 1/2" and I'm now working on an area in the range of 5/8" grinding to approximate level within 3/16" in 10',(for floating wood floor). One room has a depression that will take at least 1/2" float (for the floating wood floor). And lastly one bay of the garage has a depression of 1/2" + in a corner.

So what are current building standards for a poured concrete slab?

P.s. The pex where it enters the slab is at grade - probably not a problem in north texas, but...

Thanks for the information and great assist.

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The National Association of Home Builders "Residential Construction Performance Guidelines" states that concrete floors in living areas shall not have pits, depressions, or area of unevenness exceeding 3/8-inch in 32 inches.

Now I know may of you think these standards are poor and are really slanted toward the builder but I don't think the IRC address how level the slab should be.

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Here are AZ applicable standards, FWIW...

1. Floors should not vary from flat more than 1/4" over a 10' area provided the deviation is gradual. Deviations, dips, or sags over short distances and easily visible to the eye may be considered unacceptable.

2. Floors should be level within 1/4" in any 12' run.

Out here, we avoid running PEX through the slab. that's one of the advantages of PEX- because it's much cheaper than copper, you can run it in walls and the attic, thus avoiding supply piping leaks.

In the applicationswhen it is under slab (it see it used as a conduit for icemaker lines and for island plumbing) it should be wrapped with with a foam type material like sill seal. Direct contact w/ the concrete can cause stress due to expansion/contraction. We don't worry too much about freezing in these parts.

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