Understanding Concrete Floor Flatness Tolerances

In new construction (most commonly commercial), concrete contractors pour and set the concrete subfloor to meet a minimum flatness tolerance in accordance with American Society of Concrete Contractors (ASCC) Division 3 requirements, tested in accordance with ASTM E1155.

Division 9 specifications for concrete floor flatness tolerances specify floor flatness requirements for floor coverings and differ from Division 3 requirements. The concrete contractors seldom receive Division 9 specifications when bidding the project, because the floor covering often hasn’t been chosen yet.

Concrete contractors are responsible for meeting the requirements of Division 3 specifications for floor flatness.

ASCC, NWFA, National Tile Contractors Association (NTCA), and Flooring Contractors Association (FCICA) suggest the owner provide a bid allowance, established by the architect/design professional, and based on the floor covering requirements, for any necessary grinding and patching to close the gap between Division 3 and Division 9 tolerances. Providing this allowance enables the owner to compare floor covering bids on an equal basis.

If you have any questions about concrete floor flatness tolerances, contact your ASCC concrete contractor, the ASCC Technical Hotline at 800.331.0668, the NWFA at 800.422.4556, or the FCICA at 248.661.5015.

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