Floor system study for a project in Bangladesh

1. Cost comparison With Different
types of Slab Systems
11.2 x 11.2 Meter Panel
Scheme 1 - Conventional Flat Slab
Scheme 2 - PT Flat Slab with Drop
Scheme 3 – Waffle Slab
Scheme 4 - PT Waffle Slab

2. Scheme - 1
Conventional Flat Slab

3. Conventional Flat Slab
275MM THICK FLAT SLAB WITH 600MM THICK DROPS.
Drop size 4x4 m
LL – 4 KN/M2
SIDL – 2.5 KN/M2
APPROXIMATE COSTING FOR 11.2X11.2 MINTERNAL BAYS
CONCRETE 0.316M2/M3 @ 6500/M3 = Rs. 2054/M2
SHUTTERING 1.025 @ 650/M2 = Rs. 666.25/M2
REINFORCEMENT GRADE Fy500 26 KG/M2 @ Rs.60/Kg = Rs. 1560/M2
TOTAL = Rs. 4280.25/m2

4. Conventional Flat Slab Advantages and Disadvantages
Advantages Disadvantages
Less construction time Higher slab thickness, Higher Cost
Ease of Framework installation.
Use of drop panels may interfere
with larger mechanical ducting
Reinforcement placement is easier. Critical middle strip deflection
Building height can be reduced. Span length is medium.
Flexibility in room layout. Not suitable for supporting brittle
(masonry) partitions
Prefabricated welded mesh.
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5. Scheme - 2 PT Flat Slab with Drops

6. PT Flat Slab with Drops
250MM THICK PT FLAT SLAB WITH 600MM THICK DROPS.
DROP SIZE 4x4 M.
LL - 4 KN/M2
SIDL – 2.5 KN/M2
APPROXIMATE COSTING FOR 11.2X11.2M INTERNAL BAYS
CONCRETE 0.295 M2/M3 @ 6500/M3 = Rs. 1917.5/M2
SHUTTERING 1.025 @ 650/M2 = Rs. 666.25/M2
REINFORCEMENT GRADE Fy500 16 KG/M2 @ Rs.60/Kg = Rs. 960/M2
COST OF PT WORKS = Rs. 575/M2
TOTAL = Rs. 4118.75/M2

8. PT Slab Flat Slab with Drop Advantages and Disadvantages
Advantages Disadvantages
Lesser usage of materials
Corrosion- corrosion depends on the
quality of the material used
Reduced cost Services of Specialized PT agency
required which could affect schedule
More Durable
Future core cutting for services
restricted due to PT Tendons
Flexibility in design
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9. Scheme - 3 Waffle Slab

10. PT Waffle SlabScheme - 4
800X800X375 Waffle WITH 75MM THICK SLAB
OVERALL DEPTH = 375MM, DEPTH OF RIB = 300MM
RIB THICKNESS = 125MM AT BOTTOM, AVERAGE WIDTH=186MM
DROP THICKNESS – 500MM, Drop size 4x4 m
LL – 4 KN/M2
SIDL – 2.5 KN/M2
APPROXIMATE COSTING FOR 11.2X11.2M INTERNAL BAYS
CONCRETE 0.258 M3/M2 @ 6500/M3 = Rs. 1677/M2
COST OF MOULD PER M2 (REFER ANNEXURE) = Rs. 48.2/M2
COST OF SHUTTERING INCLUDING PROPPING = Rs. 200/M2
REINFORCEMENT GRADE Fy500 APPROX 20.73 Kg/M2 @ Rs.60/kg = Rs. 1243.8/M2
Cost of PT Tendons = Rs. 315/M2
TOTAL = Rs. 3484/M2

11. Cost of Mould
(* To be verified as per latest taxes)
Say Rs.48.2 cost/Sqm for 100 Repetition
ANNEXURE
1€ =84 INR
Sr. No Module Size Container per load Price/Mould in Euro Cost Of Load Remark
1
800x800x375m
m 1250 25 31250 €
Container transportation to Mumbai in
euro 2200 €
Total cost of load in Euro 33450 €
Cot of one mould in Euro 26.76 €
Cost of one mould in Rs. 2247.84 Rs.
Add duty 36% of mould cost in rs. 809.22 Rs.
Transportation from mumbai 30.00 Rs.
Cost of moulds 3087.06 Rs.
For 100 Repetition 30.87 RS.
Cost/sqm for 100 Repetition 48.16 RS.

13. NORTH SOUTH UNIVERSITY, BANGLADESH

14. NORTH SOUTH UNIVERSITY, BANGLADESH

16. Waffle Slab Advantages and Disadvantages
Advantages Disadvantages
Saving on weight and materials
Depth of slab between the ribs may
control the fire rating
Long Spans Requires special or proprietary
formwork
Attractive soffit appearance if
exposed
Greater floor-to-floor height
Economical when reusable formwork
pans used
Large vertical penetrations are more
difficult to handle.
Vertical penetrations between ribs
are easy.
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17. Cost of 11.2x11.2m Panel (only for floor system)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Conventional Flat
Slab
PT Flat Slab with
Drop
PT Waffle Slab
CostperSqm
Cost per Sqm

18. Additional saving Compare to Conventional Slab
SAVING IN COLUMNS DUE TO 15%
REDUCTION IN SELF WEIGHT
Rs. 300/sqm
SAVING IN FOUNDATIONS Rs. 36/sqm
(* Rate of steel and Concrete vary as per Market Rates.)
 Summary
Conventional Flat Slab Rs. 4280.25/sqm
PT Flat slab with Drop Rs. 4118.75/sqm
PT Waffle Slab Rs. 3263/sqm

19. Thank You!