Ff/Fl For Sloped Precast Parking Deck 1

[wvatecheng1]

I am specifying the topping slab for an open precast parking deck and wanted to know which (if any) Ff/Fl numbers to use for the topping slab. The precast double-tees and the topping are sloping to individual floor drains (approximately 10" drop in 60-ft length) in each bay leading me to think that the Levelness number cannot be achieved.

Is it likely that the flatness number cannot be acheived either?

Any help will be appreciated.

 

[SlideRuleEra]

For an intentionally sloped surface the F-number for level (Fl) is not used. It has no meaning since there is no attempt to make the surface level.

The Flatness number (Ff) is appropriate, but will be difficult to define since you MAY have compound slopes to individual floor drains. Ff will work if you have constant slope in one direction; such as to to a floor trench. However, I suggest assigning a "reasonable" value for Ff anyway to give the Contractor and idea of the workmanship needed. May not be enforceable, but better than nothing.

Too often, the F-number system is misused to assign absurdly high requirements for "routine" surfaces. Be careful to avoid the temptation to say, for example: "If Ff = 25 is good... Ff = 50 is better".

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[wvatecheng1]

SlideRuleEra, thanks for the advice.