1. Floor Flatness and Levelness
Chapter 4
Starts on CCS1-10 page 23

2. Chapter Topics Measuring floor flatness and levelness
The 10 ft (3m) straightedge method
F-number system
Factors affecting floor flatness and levelness

3. Definitions Flatness Levelness Waviness or bumpiness of slab surface
Smooth
Levelness
Tilt or slope of slab surface
CCS1-10 page 23 LHS

4. Measuring Flatness and Levelness
Gap under a 10 ft straightedge
Oldest method
Measures only floor flatness; not levelness
Generally less satisfactory way of measuring
F-number system
Measures floor flatness and levelness
Must be used if floor exceeds 10,000 sf (ACI 301)
Measurements in accordance with ASTM standard
CCS1-10 page 23 LHS

5. The 10 ft Straightedge Method
Measured within 72 hours
Place an unleveled 10 ft straightedge on slab
Rests on two high spots
Measure gap at any point under straightedge between two high spots
100% compliance with straightedge not realistic
Four out of five measurements more realistic
CCS!-10 page 23 LHS

6. CCS1-10 page 23 RHS

7. CCS1-10 page 23 RHS

8. F-Number System Measure within 72 hours
FF – floor flatness FL – floor levelness
To get F-numbers
Measure surface elevations at 12 inches on-center
FF (bumpiness) calculated over 24 inch length
FL (tilt) calculated over 10 ft length
F-number pair always written in order: FF/FL
Higher F-numbers: the flatter and more level
CCS1-10 page 23 RHS and page 24 LHS

9. F-number System Two different sets of F-numbers
Specified Overall Value (SOV)
Minimum Local Value (MLV)
Check specifications for requirements
ACI 302 provides recommendations
Measure in accordance with ASTM E 1155
FL should not be measured on sloped slabs
CCS1-10 page 24 LHS

10. CCS1-10 page 24

11. CCS1-10 page 24 LHS

12. CCS1-10 page 25 LHS

13. CCS1-10 page 25 RHS

14. CCS1-10 page 25 RHS

15. CCS1-10 page 25 RHS

16. Factors Affecting Flatness
Concrete workability, finishability, and setting time;
The window of finishability
Sun, wind, rain, temperature extremes,
Amount of sunlight on the slab;
Timeliness of concrete delivery;
Uniformity of concrete slump, as delivered;
Consistency of final setting time; and
Site accessibility.
CCS1-10 page 25 LHS

17. Factors Affecting Levelness
Accuracy of edge forms
Quality of initial strikeoff
Wet screeds are harder to get higher FL
Smaller strip placements are easier to get higher FL
CCS1-10 page 25 LHS and page 26 LHS and RHS

18. End of Chapter 4