Kinetics requires a specified overall value of Floor Flatness FF = 38 and a minimum local value
of Floor Flatness FF = 25. This means that locally the floor is considered “Flat” and globally the
floor is considered “Good” (“Flat” and “Good” are terms defined by ACI- American Concrete
Institute Guidelines Section 302). Conventionally this means locally a 10 foot straight edge
would have 1/4 inch of variation, and globally the variation would be less than 3/16 inch.
These requirements are necessary for Kinetics spring lift slabs because the top of the
structural floor becomes a pouring form for the bottom of the isolated slab. As the canisters
are a fixed height, inconsistencies in the structural floor become reflected in the isolated slab.
If the structural floor is not considerably flat then issues can arise that adversely affects the
acoustical, and even possibly the structural performance of the isolated, elevated slab. The
standard deviation of varying thickness of the slab could be significantly more than was
accounted for in the selection of the isolators; this could lead to under or over isolation,
incorrect leveling screw set dimensions, and structural stress in the isolated slab. This can
also make lifting the slab to a constant elevation very difficult.
Normally FL is typically specified with along with these numbers for levelness. While flatness
between mounts is critical, the slope of a floor is not nearly as crucial. Please contact Kinetics
if a sloped floor is being considered with spring isolated slabs.