Floor Flatness and Levelness and Deflection
Floor Flatness and Levelness and Deflection
(OP)
This question is a two part-er:
1.) In our concrete specifications we indicated required F(F) and F(L) numbers for floor flatness and levelness. The main reason these are spec'd is for requirements of the flooring. Per ACI 117, these measurements are to be taken at a maximum of 72 hours after the concrete has been poured (ie, prior to shoring being removed). I understand that this is a measure of the quality of the finish, but won't deflection play a large role in this number? Doesn't the service life deflection have a lot to do with the application of the flooring?
2.) Flooring specs often refer to the old "x" of deflection over 10' " as opposed to F(F) and F(L) numbers. Is this just a disconnect in the industry?
Overall, I'm just not sure what people are seeing, and what problems/solutions have come up. [color #FCE94F][/color]Thanks in advance!
1.) In our concrete specifications we indicated required F(F) and F(L) numbers for floor flatness and levelness. The main reason these are spec'd is for requirements of the flooring. Per ACI 117, these measurements are to be taken at a maximum of 72 hours after the concrete has been poured (ie, prior to shoring being removed). I understand that this is a measure of the quality of the finish, but won't deflection play a large role in this number? Doesn't the service life deflection have a lot to do with the application of the flooring?
2.) Flooring specs often refer to the old "x" of deflection over 10' " as opposed to F(F) and F(L) numbers. Is this just a disconnect in the industry?
Overall, I'm just not sure what people are seeing, and what problems/solutions have come up. [color #FCE94F][/color]Thanks in advance!






RE: Floor Flatness and Levelness and Deflection
FF & FL numbers are a specification and how well they are achieved is a measure of the contractor's ability to perform.
Actual structure deflection (of elevated slabs) reflects back on the designer's ability to anticipate the structure's performance and provide a proper design.
Structure deflection may have an impact on the flooring, but it will depend upon what the specific flooring is.
Ralph
Structures Consulting
Northeast USA
RE: Floor Flatness and Levelness and Deflection
RE: Floor Flatness and Levelness and Deflection
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Floor Flatness and Levelness and Deflection
Dave
Thaidavid
RE: Floor Flatness and Levelness and Deflection
thaidavid40 - I agree that the contractor should be responsible for concrete overruns needed because of formwork/shoring deflections. However, If the FL numbers are found to be satisfactory prior to the removal of formwork/shoring, any subsequent leveling mixes required because of the structural deflection should not be the contractor's responsibility.
Ralph
Structures Consulting
Northeast USA
RE: Floor Flatness and Levelness and Deflection
Ff and Fl are generally not related to load induced deflection as they are to be measured while the floor is fully supported and not loaded.