Thumb Rules Formula for Civil Engineers And Quantity Surveyors
Thumb rules play are very important rules while taking quick decision on the site. With the help of thumb rules, u can solve the solution very quickly & by using simple mathematical formulas. It can’t give u the accurate value but it can give approximate values. There are a lot of thumb rules used in the construction by civil engineers. While performing thumb rules, the units are not always same, so never consider units in thumb rule.
Basically thumb rules is the guide for Civil Engineers for the predictable results. It can vary to some percent but it will give a general idea as well. When we compare to get the result, the units in thumb rules are not the same. Therefore, never consider units when performing the thumb rules. There are several thumb rules that we apply in the Construction. Here I m discussing the most frequently used thumb rules on the Site.
There are a lot of thumb rules charts used in Construction Site but few of the thumb rules are used in Construction by Civil Engineers. Following are some of these charts given with an example.
Thumb Rule for Cement, Sand, Coarse Aggregate Quantity in Different Grades of the Concrete.
You can easily calculate the QTY of Cement, Sand, Coarse Aggregate for the specific Grades of Concrete using the following chart.
S. No 
Grade of Concrete 
Cement (Bags) 
Sand (m^{3}) 
Coarse aggregate (m^{3}) 
1 
M5 (1:5:10) 
2.82 
0.49 
0.98 
2 
M7.5(1:4:8) 
3.48 
0.48 
0.97 
3 
M10(1:3:6) 
4.50 
0.45 
0.90 
4 
M15(1:2:4) 
6.60 
0.44 
0.88 
5 
M20(1:1.5:3) 
8.40 
0.42 
0.84 
Example
To find the materials for M5 grade of the concrete we will take an example for the better understanding.
Let, the volume (of the slab) is 10 m^{3}
First we will find the QTY of cement
Cement = volume x 2.82 (table value)
Cement = 10 x 2.82
Cement = 28.2 bags
Now, we will find the QTY of sand
Sand = volume x 0.49 (table value)
Sand = 10 x 0.49
Sand = 49 m^{3}
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Now, we will find the QTY of Coarse Aggregate
Coarse aggregate = volume x 0.98 (table value)
Coarse aggregate = 10 x 0.98
Coarse aggregate = 98 m^{3}
Thumb Rule for Steel in Reinforcement Concrete.
The Steel is very expensive than the other Constructions materials. It is very expensive to purchase excessive Steel Coz purchase of the extra steel will impact the budget of project very badly. There are some thumb rule charts to find steel in Reinforcement Concrete ( R.C.C ) Structures that is given.
Thumb Rule for Steel in Reinforcement Concrete ( R.C.C ) Structures
S. No 
Type of structure 
Steel ( Kg/ft^{2 }) 
1 
Residential Building 
2.5 – 4.5 
2 
Commercial Building 
4.5 – 5.5 
3 
Heavy Structure 
6 – 8 
Example
Let’s take an example to find the steel for residential buildings
Area of residential building is 100 m^{2}
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Steel in the residential building = volume x 2.5 (table value)
Steel in residential building = 100 x 2.5
Steel in residential building = 25 kg
Thumb Rule for Steel in ( R.C.C ) Members
S. No 
Structural members 
Percent of steel (%) 
1 
Slab 
1 % 
2 
Beam 
1 – 2% 
3 
Column 
2.5 % 
Example
To find the steel in the structural members such as slab, beam & column the steps are given.
In this example, we will find the steel for the slab. The volume of the concrete in the slab is 100 m^{3}
Step 1…
Steel QTY of slab = Volume of the Concrete x Density of Steel x % of Steel of Member
Steel QTY of slab = 100 x 7850 x 1%
Steel QTY of slab = 7850 kgs
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Thumb Rule for the Masonry Work
The Masonry work include bricks, mortar & plaster. The composition of the mortar & plaster is cement and sand. There are different thumb rules used for the plaster materials & mortar materials
Thumb Rule for No. of Bricks
No. of bricks = 500 per m3
Example
To find the brick let’s take an example for better understanding suppose the volume of the wall is ten m^{3}
No. of bricks = Volume of wall x 500
No. of bricks = 10 x 500
No. of bricks = 5000
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Thumb Rule for the Plastering Work
The following is the chart used for Calculation of the plastering material (cement and sand) for different types plastering work.
S. No 
Type of plastering 
Ratio 
Thickness of plastering (mm) 
Cement (bags) 
Sand (m^{3}) 
1 
Inner 
1:3 
15 
0.16 
0.017 
2 
External 
1:4 
20 
0.17 
0.024 
3 
Rough 
1:5 
16 
0.11 
0.020 
4 
Ceiling 
1:2 
12 
0.17 
0.012 
Example
To find the plastering materials, let’s take an example for the better understanding. Suppose the area of the wall is ten m^{2}
Finding the materials for the inner plastering first step is to find cement
Calculation of Cement
Cement = Area x 0.16 (table value)
cement = 10 x 0.16
cement = 1.6 bags
Calculation of Sand
sand = Area x 0.017 (table value)
sand = 10 x 0.017
sand = 0.17 m^{3}
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Thumb Rule for the Mortar Work
This chart provides values used for the calculation of mortar materials for various mix ratios;
S. No 
Mix Ratio 
Cement (bags) 
Sand (ft^{3}) 
1 
1:3 
0.06 
0.225 
2 
1:4 
0.047 
0.24 
3 
1:5 
0.04 
0.25 
4 
1:6 
0.03 
0.26 
5 
1:8 
0.026 
0.27 
6 
1:10 
0.020 
0.275 
Example
To find the mortar materials, let’s take an example for better understanding. Suppose the volume of the wall is 100ft^{3}. Find the materials for 1:3 Mix Design.
The first step is to find the QTY of cement
Calculation for the Cement
Cement = Volume x 0.06 (table value)
Cement = 100 x 0.06
Cement = 6 bags
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Calculation of the Sand
Sand = volume x 0.225 (table value)
Sand = 100 x 0.225
Sand = 22.5ft^{3}
Thumb Rule for the Shuttering
There are different components in the shuttering & different thumb rules that is used in the shuttering is given below
Thumb Rule for the Shuttering Oil
The following equation is used for the calculation of the shuttering oil for a specific area.
Total Shuttering oil is required = 0.065 x Total Area of Shuttering (m^{2})
Example
To find the shuttering oil, let’s take an example for the better understanding. Suppose the area of shuttering is 100 m^{2}.
Shuttering oil = Area x 0.065
Shuttering oil = 100 x 0.065
Shuttering oil = 6.5 liter
Thumb Rule for the Shuttering Removal
The following chart provides the details about shuttering removal after a specific duration for different structures.
S. No 
Members of structure 
Days 
1 
Sides of foundation, beam, columns and walls 
2 days 
2 
Sides of slab under 4.5 meter span 
7 days 
3 
Sides of slab above 4.5 meter span 
14 days 
4 
Side of beams and arches up to 6 meter span 
14 days 
5 
Side of beams between 6 meter to 9 meter span 
21 days 
6 
Side of beams and arches above 9 met 
28 days 
Thumb Rule for the Shuttering Nails and Binding Wire
The following QTY of nails and binding wire is used in the shuttering per unit area.
75gms of the Nails are used for 1m^{2} of Shuttering
75gms of the Binding wire is consumed for every 1m^{2} of the Shuttering.
Example
To find the shuttering nails or binding wire, let’s take an example for the better understanding. Suppose the area of shuttering is 100 m^{2}_{.}
Shuttering Nails = Area x 75
Shuttering Nails = 100 x 75
Shuttering Nails = 750 gms
Calculation for the binding wire used in shuttering
Shuttering binding wire = Area x 75
Shuttering binding wire = 100 x 75
Shuttering binding wire = 750 gms
Shuttering Ply QTY Calculation
The quantity of shuttering ply can be calculated using the following equation.
No. of Shuttering Ply sheets = 0.22 times of the Shuttering (m^{2})
Example
To find the shuttering ply QTY , let’s take an example for the better understanding. Suppose the area of the shuttering is 100m^{2}
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No. of shuttering ply sheets = (Area x 0.22) / Area of ply sheet
No. of shuttering ply sheets = 100 x 0.22 / Area of ply sheet
No. of shuttering ply sheets = 22 / Area of ply sheet
Battens Quantity Calculation
The number of the batten QTY can be calculated using the following equation
Batten QTY = 19.82 x No. of Ply Sheets
Example
To find the shuttering batten QTY, let’s take an example for the better understanding suppose the number of shuttering ply sheets is ten.
Batten QTY = No. of Ply Sheets x 19.82
Batten QTY =10 x 19.82
Batten QTY =198.2 Nos
Thumb Rules For Civil Engineers for the Brickwork
following the Thumb Rules for civil engineering for brickwork & Cement QTY Calculations.
Brickwork for 1m^{3} 
Cement Qty in m^{3} 
Cement Qty in Bags 
230 mm Brickwork 
0.876m^{3} 
25.4 Bags 
115 mm Brickwork 
0.218m^{3} 
6.32 Bags 
Thumb Rules For Cement Masonry QTY
Cement Masonry Type and Mix 
Cement Qty in Bags 
Cement Qty in Kgs 
200mm in Cement Masonry workof Ratio 1:6 
0.124Bags/m^{2} 
6.2Kgs/m^{2} 
150mm in Cement Masonry workof Ratio 1:6 
0.093Bags/m^{2} 
4.65Kgs/m^{2} 
200mm in Cement Masonry workof Ratio 1:4 
0.206Bags/m^{2} 
10.3Kgs/m^{2} 
150mm in Cement Masonry workof Ratio 1:4 
0.144Bags/m^{2} 
7.2Kgs/m^{2} 
100mm in Cement Masonry workof Ratio 1:4 
0.103Bags/m^{2} 
5.15Kgs/m^{2} 
Thumb Rules Plastering QTY.
Type of Plastering 
Cement Qty in Bags 
Cement Qty in Kgs 
Rough Plastering 
0.09Bags/m^{2} 
4. 5Kgs/m^{2} 
Internal Wall Plastering 
0.09Bags/m^{2} 
4.5Kgs/m^{2} 
Duct Plastering 
0.09Bags/m^{2} 
4.5Kgs/m^{2} 
External Wall plastering 
0.175Bags/m^{2} 
8.75Kgs/m^{2} 
Stucco Plastering 
0.175Bags/m^{2} 
8.75Kgs/m^{2} 
Lathen Plastering 
0.55 Bags/m^{2} 
27.5 Kgs/m^{2} 
How do you calculate the steel by thumb rules?
Following are Thumb Rules for Reinforcement Steel in the concrete members,
1) Slab – 1% of the total volume of the concrete (Slab steel calculation thumb rule)
2) Beam – 2% of the total volume of the concrete
3) Column – 2.5% of the total volume of the concrete
4) Footings – 0.8% of the total volume of the concrete
What is the good rule of thumb.?
Thumb Rules can be called a guideline, idea, or principle that helps u make quick decisions. Arrive early is an efficient good Thumb Rules for the most appointments. It referred to builders who frequently use their thumb to estimates measurements. It is a helpful rules even being inexact.
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What is the basic knowledge For Civil Engineering.?
Civil Engineers Must Know
1. Lapping in Reinforcement is not allowed for the bars having diameters more than 36mm.
2. Steel Char maximum spacing is 1.00m or 1No per 1m2.
3. In steel dowels, a rod minimum of the 12mm diameter should be used.
4. Steel Chairs minimum of the 12mm diameter bars to be used.
5. Longitudinal Reinforcement should not be less than 0.8% & more than Six% of gross C/S.
6. The minimum bars used for square column are four No’s & Six No’s for the circular column.
What is the thumb rules to determine beam depth.?
The method for the determining the widthdepth ratio of the reinforced Concrete Beams is not specifically given in codes. However, a thumb rules can be used i.e taking depth that is 2 & a half to 3 times the beam’s width. For longspan beams, it is generally economical to use the deep & narrow sections.
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Thumb Rules For Civil Site Engineering pdf
Thumb Rules For Civil Engineering pdf is essential for any Civil Engineer, Site Engineer, or Civil Supervisor. They play a crucial role the while taking quick decisions on the site. There is some civil Engineering basic knowledge that every Civil Engineers must know.
Thumb Rule Requirement of the Standard Materials & Standard Calculation in high Raised building.
Steel =3 to 5 kg / sqft.
Cement =0.5bags/ sqft.
RMC =0.05 m3/sqft.
Block =12.5 nos /sqm.
Electrical cast = Rs 133/sqft.
Plumbing cost = Rs 126/sqft.
Fire fighting cost = Rs 40/sqft.
External development = Rs 94.5/sqft.
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