CONCRETE SPECS & FLOOR FLATNESS
CONCRETE SPECS & FLOOR FLATNESS
(OP)
Does anyone have any advice on specifying floor flatness for unshored elevated slabs in general office buildings? What is the difference between overall values of flatness and levelness vs. local value of flatness and levelness? I am specifying F(F)=25 & F(L)=20 for overall value...what should I specify for loca values? & is anything really specified for levelness in an unshored slabs?






RE: CONCRETE SPECS & FLOOR FLATNESS
In the UK BS5606:1990 Guide to accuracy in buildings might be of some use. Flatness of in situ floors is usually around 5mm deviation over a 3m length but you need to check what is acceptable for you location.
In addition you would find guidance in the National Structural Concrete Specification for Building Construction (ISBN 0 7210 1571 9). Section 7 covers construction accuracy with things like twist, squareness, position, level, verticality, bow etc. Again this is a UK document but I would imagine there is something similiar in you area.
RE: CONCRETE SPECS & FLOOR FLATNESS
RE: CONCRETE SPECS & FLOOR FLATNESS
ACI 302.1R "Guide for Concrete Floor and Slab Construction"
ACI 117-90 "Standard Specifications for Tolerances for Concrete Construction and Materials"
RE: CONCRETE SPECS & FLOOR FLATNESS
I do know that trying to obtain an overall value of FF25/FL20 is very hard (as our spec is the same) and the local labor here never achieved it. As a consequence we are going to have to do a lot of grining and filling to satisfy the client.
Unless you are very certian about your contractor's capabilities you might want to consider lowering the slab a bit and using a self leveling topping.
RE: CONCRETE SPECS & FLOOR FLATNESS
Contractors and suncontractors who specialize in such formwork and placement are often much more aware of when why and how a slab is to be tested. If your specs or methodology is questioned, do make sure you understand why you are specfying such numbers.
Best of luck,
Daniel Toon