Thumb Rules used in Construction For Civil Engineers | Read Here
Thumb rule to calculate the Steel quantity required for Slab, Beams, Footings & Columns:
For Residential buildings :- 4.5Kgs-4.75Kgs /SFT
For Commercial buildings :- 5.0Kgs-5.50Kgs/SFT
As per B N Datta, the Steel quantity used in different members of the building can be calculated easily using the following recommendations.
| Structural Member | Percentage of Steel |
|---|---|
| Slab | 1% of total volume of concrete |
| Beam | 2% of of total volume of concrete |
| Column | 2.5% of total volume of concrete |
| Footings | 0.8% of total volume of concrete |
Example:
How to calculate the steel quantity of slab having the Length, width, and depth of the slab is 5m x 2m x 0.15m
Step 1: Calculate the Volume of Concrete
Total Volume of Concrete for above given Slab is 5 x 2x 0.15 = 1.5 m3
Step 2: Calculate the steel quantity using formula
As per the above table, the steel quantity of slab is 1% of the total volume of concrete utilized.
Thumb rule to calculate Steel quantity of above slab = Volume of Concrete x Density of Steel x % of Steel of Member
Steel quantity required for above slab = 1.5 x 7850 x 0.01 = 117.7 Kgs
Thumb rule for Cement, Sand, Coarse Aggregate Quantity in Different grades of Concrete :
| Concrete Mix | Cement Quantity | Coarse Aggregate Quantity | Fine Aggregate Quantity |
|---|---|---|---|
| M5 (1:5:10) | 2.82 Bags | 0.98m3 | 0.49m3 |
| M7.5(1:4:8) | 3.48 Bags | 0.97m3 | 0.48m3 |
| M10(1:3:6) | 4.50 Bags | 0.90m3 | 0.45m3 |
| M15(1:2:4) | 6.60 Bags | 0.88m3 | 0.44m3 |
| M20(1:1.5:3) | 8.40 Bags | 0.84m3 | 0.42m3 |
Note: 1 bag of cement = 50Kgs
Thumb rule to calculate the Concrete Volume with respect to area:
The Concrete Volume of 0.038m3 of concrete is used for each Square Feet of Plan area
Example:-
From below fig: Plan Area = 20 x 20 = 400SFT
The plan area is 400SFT then the total volume of concrete required = 400 x 0.038m3 = 15.2 m3
Thumb rule for Cement quantity in Brickwork, Cement Masonry & Plastering work in construction:
Brickwork Thumb rule:
| Brickwork for 1m3 | Cement Qty in m3 | Cement Qty in Bags |
|---|---|---|
| 230 mm Brickwork | 0.876bags/m3 | 43.80kgs |
| 115 mm Brickwork | 0.218bags/m3 | 10.90kgs |
Cement Masonry Quantity Thumb Rule:
| Cement Masonry Type & Mix | Cement Qty in Bags | Cement Qty in Kgs |
|---|---|---|
| 200mm in Cement Masonry work of ratio 1:6 | 0.124Bags/m2 | 6.2Kgs/m2 |
| 150mm in Cement Masonry work of ratio 1:6 | 0.093Bags/m2 | 4.65Kgs/m2 |
| 200mm in Cement Masonry work of ratio 1:4 | 0.206Bags/m2 | 10.3Kgs/m2 |
| 150mm in Cement Masonry work of ratio 1:4 | 0.144Bags/m2 | 7.2Kgs/m2 |
| 100mm in Cement Masonry work of ratio 1:4 | 0.103Bags/m2 | 5.15Kgs/m2 |
Plastering Quantity Thumb Rule:
| Type of Plastering | Cement Qty in Bags | Cement Qty in Kgs |
|---|---|---|
| Rough Plastering | 0.09Bags/m2 | 4.5Kgs/m2 |
| Internal Wall Plastering | 0.09Bags/m2 | 4.5Kgs/m2 |
| Duct Plastering | 0.09Bags/m2 | 4.5Kgs/m2 |
| External Wall plastering | 0.175Bags/m2 | 8.75Kgs/m2 |
| Stucco Plastering | 0.175Bags/m2 | 8.75Kgs/m2 |
| Lathen Plastering | 0.55Bags/m2 | 27.5Kgs/m2 |
Thumb rule to calculate the Shuttering area:
Shuttering costs 15-18% of the total construction of the building. Shuttering is framed to bring the concrete in Shape. Thumb rule to calculate the shuttering required is 6 times the quantity of concrete or 2.4 times of Plinth area.
Suppose, the concrete quantity is 1.5 m3 then the shuttering area required is 1.5 x 6 = 9m2
Components of Shuttering:-
Shuttering Ply, Battens, Nails are components of Shuttering.
Shuttering Ply Quantity calculation:
The shuttering Ply has a length, width & depth of 2.44 x 1.22 x 0.012
The No. of Shuttering Ply sheets = 0.22 times of Shuttering
Suppose, the area of shuttering required = 2m2
Then the Shuttering Ply required = 0.22 x 2 = 0.44 m2
Battens Quantity Calculation:
Shuttering batten usually have a length & width of 75mm x 40mm.
Batten Quantity = 19.82 x No. of Ply Sheets
if the construction requires 25 Ply sheets, the total quantity of Battens are 19.82 x 25 = 495 Battens
Nails & Binding Wire Quantity in Shuttering:
75gms of Nails are used for 1m2 of Shuttering
75gms of Binding wire is consumed for every 1m2 of Shuttering.
Thumb rule for Shuttering oil Quantity:
Shuttering oil is used to de-frame or de-assemble from the concrete easily.
Total required Shuttering oil is = 0.065 x Total Area of Shuttering
(or)
For every 15m2 of shuttering 1 litre of shuttering oil is consumed.
Example :
10m2 is total area of shuttering, then Shuttering oil required = 0.065 x 10 = 0.65 lts