ACI Top of Floor Slab Tolerance

[drm4444]

My 6 story building has top of floor slab elevations off as much as 3". Generally, the survey indicates most areas are within 1/2" but there are several locations on several floors where the top of slab elevation is up to 3" too high or low. The spec references ACI & AISC for the appropriate tolerances. Anyone know what the max is? Maybe in ACI 117?

 

[ishvaaag]

So is the opinion of the

Manual de la Construcción con Hormigón, 3ª Ed.
Waddell, Dobrowolski
Mc Graw Hill

See attachment

 

[mijowe]

I believe 3/4" is the number for the top of slab elevation(prior to removal of shores). But sounds like you have flatness and levelness issues as well.

Do the high points align up and down the building?

This could be tricky at the perimeter if you have floor to floor glass, or if you have brick relief attached to the slab.

 

[ishvaaag]

In ACI 117

Max Vertical deviation of any elements +/- 1 in (Section 4.2.2) except at edges of openings that +/- 1/2 in
Thickness of suspended slabs tolerance is -1/4 in (Section 4.5.3)
Max irregularity over the distance of 10 ft +/- 0.3% (Section 4.8.2)

 

[drm4444]

I have slab on metal deck (no shoring). Would this also be 3/4"? I am most concerned about the curtainwall at the perimeter having enough vertical adjustment.

 

[dcarr82775]

I do not think you can apply ACI 117 tolerances to the top surface of a concrete slab on deck (there is no shoring). Did you specify a constant thickness slab, or a level slab? Since the whole system deflects it makes a difference.

I think a realistically 3/4" is a good number. 3" is so far out of a reasonable tolerance

 

[mijowe]

The above tolerances are from ACI, sounds like you have steel beams that were placed either high or low. The last time I dealt with this I concluded that the top of foundations were set either high or low, the elevation change was not corrected when the columns were set, and the beams framed into the columns the only place they could, high or low at the connections.

you probably want to look at AISC tolerances.

 

[mijowe]

^^^^ it is also possible that if the high points are at columns and the low points are at mid span that you have a deflection problem.