**Important Thumb Rules used in Construction by Civil Engineers**

Thumb rule play very important rule while taking quick decision on site. With the help of thumb rules, you can solve the solution very quickly and by using simple mathematical formula. It can’t give you the accurate value but it can give approximate value. There are a lot of thumb rules used in construction by civil engineers. While performing thumb rule, the units are not always same, so never consider units in thumb rules.

Table of Contents

There are a lot of thumb rule’s charts used on 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 Concrete**

You can easily calculate the quantity of cement, sand, coarse aggregate for 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 |

**Must Read: **What is water cement Ratio

**Example:**

To find the materials for M5 grade of concrete we will take an example for better understanding;

Let, the volume (of the slab) is **10 m ^{3}**

First we will find the **quantity of cement**

Cement = volume x 2.82 (table value)

Cement = 10 x 2.82

Cement = 28.2 bags

Now, we will find the **quantity of sand**

Sand = volume x 0.49 (table value)

Sand = 10 x 0.49

Sand = 49 m^{3}

Now, we will find the **quantity 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 RCC (Reinforcement Concrete)**

The steel is very expensive than the other construction materials. It is very expensive to purchase excessive steel because purchase of extra steel will impact the budget of project very badly. There are some thumb rule charts to find steel in reinforcement concrete (RCC) structures that is given.

**Thumb Rule for Steel in RCC 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 steel for residential buildings

Area of residential building is 100 m^{2}

**Steel in 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 RCC 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 structural members such as slab, beam and column the steps are given:

In this example, we will find the steel for slab. The volume of concrete in slab is 100 m^{3}

Step 1:

**Steel quantity of slab = Volume of Concrete x Density of Steel x % of Steel of Member**

Steel quantity of slab = 100 x 7850 x 1%

Steel quantity of slab = 7850 kgs

**Thumb Rule for Masonry Work**

Masonry work include bricks, mortar and plaster. The composition of mortar and plaster is cement and sand. There are different thumb rules used for plaster materials and mortar materials

**Thumb Rule for No. of Bricks**

**No. of bricks = 500 per cubic meter**

**Example:**

To find the brick let’s take an example for better understanding suppose the volume of wall is 10 m^{3}

**No. of bricks = Volume of wall x 500**

No. of bricks = 10 x 500

No. of bricks = 5000

**Thumb Rule for Plastering Work**

The following is the chart used for calculation of plastering material (cement & 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 better understanding. Suppose the area of wall is 10 m^{2}

Finding the materials for **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}

**Thumb Rule for 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 wall is 100 ft^{3}. Find the materials for 1:3 mix design.

The first step is to find quantity of cement

**Calculation for Cement**

**Cement = Volume x 0.06 (table value)**

Cement = 100 x 0.06

Cement = 6 bags

**Calculation of Sand**

**Sand = volume x 0.225** **(table value)**

Sand = 100 x 0.225

Sand = 22.5 ft^{3}

**Thumb Rule for Shuttering**

There are different components in shuttering and different thumb rules that is used in shuttering is given below

**Thumb Rule for Shuttering Oil**

The following equation is used for the calculation of 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 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 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 Shuttering Nails & Binding Wire**

The following quantity of nails & binding wire is used in shuttering per unit area.

**75gms of Nails are used for 1m**^{2}** of Shuttering**

**75gms of Binding wire is consumed for every 1m**^{2}** of Shuttering.**

**Example:**

To find the shuttering nails or binding wire, let’s take an example for 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 binding wire used in shuttering

**Shuttering binding wire =** **Area x 75**

Shuttering binding wire = 100 x 75

Shuttering binding wire = 750 gms

**Shuttering Ply Quantity Calculation:**

The quantity of shuttering ply can be calculated using the following equation.

**No. of Shuttering Ply sheets = 0.22 times of Shuttering (m ^{2})**

**Example:**

To find the shuttering ply quantity, let’s take an example for better understanding. Suppose the area of shuttering is 100 m^{2}

**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 batten quantity can be calculated using the following equation

**Batten Quantity = 19.82 x No. of Ply Sheets**

**Example:**

To find the shuttering batten quantity, let’s take an example for better understanding suppose the number of shuttering ply sheets is 10.

**Batten Quantity = No. of Ply Sheets x 19.82**

Batten Quantity =10 x 19.82

Batten Quantity =198.2 Nos

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