This document compares the costs of different slab systems for a 10.8m x 10.8m panel. It analyzes the costs of a conventional flat slab, waffle slab, post-tensioned flat slab with drops, and post-tensioned voided flat slab. The waffle slab is the most cost effective at Rs. 3547.5/sqm, offering savings on weight and materials over the conventional flat slab which costs Rs. 4122.75/sqm. While the PT voided flat slab and PT flat slab with drops have higher costs of Rs. 4078.2/sqm and Rs. 4265.75/sqm respectively. Additional savings can be achieved with the waffle

1. Cost comparison With Different
types of Slab Systems
10.8 x 10.8 Meter Panel
Scheme 1 - Conventional Flat Slab
Scheme 2 - Waffle Slab
Scheme 3 - PT Flat Slab with Drop
Scheme 4 - PT Voided Flat Slab
Scheme 5 - Steel Building

2. Scheme - 1
Conventional Flat Slab
275MM THICK FLAT SLAB WITH 600MM THICK DROPS.
Drop size 3.6x3.6m
LL – 4.5 KN/M2
SIDL – 3 KN/M2
APPROXIMATE COSTING FOR 10.8X10.8MINTERNAL BAYS
CONCRETE 0.311M2/M3 @ 6500/M3 = Rs. 2021.5/M2
SHUTTERING 1.025 @ 650/M2 = Rs. 666.25/M2
REINFORCEMENT GRADE Fy500 28.7 KG/M2 @ Rs.50/Kg = Rs. 1435/M2
TOTAL = Rs. 4122.75/M2

4. Waffle Slab With Drop
800X800X500 WAFFEL WITH 100MM THICK SLAB
OVERALL DEPTH = 500MM, DEPTH OF RIB = 400MM
RIB THICKNESS = 125MM AT BOTTOM, AVERAGE THICKNESS=208MM
DROP THICKNESS – 500MM, Drop size 3.6x3.6m
LL – 4.5 KN/M2
SIDL – 3 KN/M2
APPROXIMATE COSTING FOR 10.8X10.8MINTERNAL BAYS
CONCRETE 0.305 M3/M2 @ 6500/M3 = Rs. 1982.5/M2
COST OF MOULD PER M2 (REFER ANNEXURE) = Rs. 65/M2
COST OF SHUTTERING INCLUDING PROPPING = Rs. 200/M2
REINFORCEMENT GRADE Fy500 APPROX 26 Kg/M2 @ Rs.50/kg = Rs. 1300/M2
TOTAL = Rs. 3547.5/M2
Scheme - 2

7. Cost of Moulds
(* To be verified as per latest taxes)
Say Rs.42.2 cost/Sqm for 100 Repetition
ANNEXURE

8. NORTH SOUTH UNIVERSITY, BANGLADESH

9. NORTH SOUTH UNIVERSITY, BANGLADESH

10. Waffel Slab Advantages
Advantages
Saving on weight and materials
Long Spans
Attractive soffit appearance if exposed
Economical when reusable formwork pans used
Vertical penetrations between ribs are easy.

11. Flat slab panels with PT & Drops
275MM THICK PT FLAT SLAB & 475MM THICK DROPS.
Drop Size – 4.8x4.15m.
LL – 4.5 KN/M2
SIDL – 3 KN/M2
APPROXIMATE COSTING FOR 10.8X10.8MINTERNAL BAYS
CONCRETE 0.335 M3/M2 @ 6500/M3 = Rs. 2177.5/M2
SHUTTERING 1.025 @ 650/M2 = Rs. 666.25/M2
REINFORCEMENT GRADE Fy500 14 KG/M2 @ Rs.50/Kg = Rs. 700/M2
COST OF PT WORKS = Rs. 722/M2
TOTAL = Rs. 4265.75/M2
Scheme - 3

13. PT Voided Flat Slab
Scheme - 4
350MM THICK PT VOIDED FLAT SLAB
LL – 4.5 KN/M2
SIDL – 3 KN/M2
APPROXIMATE COSTING FOR 10.8X10.8MINTERNAL BAYS
CONCRETE 0.297 M3/M2 @ 6500/M3 = Rs. 1930.5/M2
SHUTTERING 1.025 @ 650/M2 = Rs. 666.25/M2
REINFORCEMENT GRADE Fy500 17.75 KG/M2 @ Rs.50/Kg = Rs. 887.5/M2
COST OF PT WORKS = Rs. 593.95/M2
TOTAL = Rs. 4078.2/M2

16. Cost of 10.8mX10.8m Panel (only for floor system)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
Conventional
Flat Slab
Waffel Slab
With Drop
Flat slab panels
with PT &
Drops
PT Voided Flat
Slab
CostperSqm
Cost per Sqm
Scheme 1 Scheme 2 Scheme 3 Scheme 4

17. Additional saving in Waffle Slab
SAVING IN COLUMNS DUE TO 15%
REDUCTION IN SELF WEIGHT
Rs. 300/sqm
SAVING IN FOUNDATIONS Rs. 36/sqm
 Summary
Conventional Flat Slab Rs. 4122.75/sqm
Waffel Slab With Drop Rs. 3547.5/sqm
Flat Slab Panels With PT & Drop Rs. 4265.75/sqm
PT Voided Flat slab Rs. 4078.2/sqm
(* Rate of steel and Concrete vary as per Market Rates.)

18. Thank You!