The Concrete Floor Tolerance/Floor Covering Conundrum

摘要

The following scenario is sometimes played out on construction projects that require concrete floors to receive a floor covering. In accordance with ACI 117-90, "Standard Specifications for Tolerances for Concrete Construction and Materials," an engineer specifies the following floor flatness and levelness tolerances for a hard-troweled flat floor: overall F_F30 and F_F 20 with minimum local values of F_F 15 and F_F 10. No one questions these specifications during the prebid or preconstruction concrete meeting. The concrete contractor places the floor and, within 72 h of the pour, measures the F-numbers in accordance with ASTM E 1155, "Standard Test Method for Determining F_F Floor Flatness and F_F Floor Levelness Numbers." The measured F-numbers meet the Division 3 specification requirements, and the engineer signs off on the flatness result.