ACI 301

[Steve]

I am trying to resolve a dispute between concrete sub and owner regarding floor flatness.
Spec is ACI 301, Section 11.9, Class B tolerance. I don't have a copy of ACI 301. Anyone know what the requirements are for Class B tolerance. Also, the concrete sub told me this is an old spec and the ACI floor flatness standards have changed. Anyone know if this is correct.

Thanks for your help

Steve

[William Wiehe]

Steve,
The link below should point you to a table (ACI 17) that specifies chart for floor "flatness". Different floor "uses" call for different flatness tolerances. Usually, flooring manufacturers will refer to these Ff spec's to ensure proper installations of their products. Based on what I have read, it seems to me that hardwood flooring manufactures are the most particular and like to see a Ff50 which is no more than an 1/8" gap or "birdbath" under a 10 foot non-level straight edge. That would be a darn flat floor.
Residentially (and practically)speaking, if you get your concrete contractor to place and finish your slab to within a 1/4" gap of a 6' straight edge, your doin' pretty good.
At any rate, hopefully your owner and sub are doing well to debate this tolerance BEFORE rather than after the concrete pour.
William


ACI 17