Basic Thumb Rules For Civil Engineers

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 (m3)	Coarse aggregate (m3)
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 M-5 grade of the concrete we will take an example for the better understanding.

Let, the volume (of the slab) is 10 m³

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 m³

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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 m³

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/ft2 )
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 m²

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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 m³

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 m³

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 (m3)
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 m²

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 m³

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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 (ft3)
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 100-ft³. 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 = 22.5-ft³

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 (m²)

Example

To find the shuttering oil, let’s take an example for the better understanding. Suppose the area of shuttering is 100 m².

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.

75-gms of the Nails are used for 1-m² of Shuttering

75-gms of the Binding wire is consumed for every 1-m² 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 m²_.

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 (m²)

Example

To find the shuttering ply QTY , let’s take an example for the better understanding. Suppose the area of the shuttering is 100-m²

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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 1m3	Cement Qty in m3	Cement Qty in Bags
230 mm Brickwork	0.876m3	25.4 Bags
115 mm Brickwork	0.218m3	6.32 Bags

 

Thumb Rules For Cement Masonry QTY

Cement Masonry Type and Mix	Cement Qty in Bags	Cement Qty in Kgs
200-mm in Cement Masonry work of Ratio 1:6	0.124Bags/m2	6.2Kgs/m2
150-mm in Cement Masonry work of Ratio 1:6	0.093Bags/m2	4.65Kgs/m2
200-mm in Cement Masonry work of Ratio 1:4	0.206Bags/m2	10.3Kgs/m2
150-mm in Cement Masonry work of Ratio 1:4	0.144Bags/m2	7.2Kgs/m2
100-mm in Cement Masonry work of Ratio 1:4	0.103Bags/m2	5.15Kgs/m2

 

Thumb Rules Plastering QTY.

Type of Plastering	Cement Qty in Bags	Cement Qty in Kgs
Rough Plastering	0.09-Bags/m2	4. 5-Kgs/m2
Internal Wall Plastering	0.09-Bags/m2	4.5-Kgs/m2
Duct Plastering	0.09-Bags/m2	4.5-Kgs/m2
External Wall plastering	0.175-Bags/m2	8.75-Kgs/m2
Stucco Plastering	0.175-Bags/m2	8.75-Kgs/m2
Lathen Plastering	0.55 Bags/m2	27.5 Kgs/m2