Size of column depend upon several factors like load on the **structure, height of the building and distance between the two column**. In this post we will discuss standard size of Column for building construction.

**Size of the column **also depends upon the material used in column construction. Column based on material are classified as RCC column, timber column, short column, tied column and many more.

## Standard Size Of Column

As stated above **standard size of column** depends upon many factors. But for rough idea of column size refer the table below. Detailed information about standard size of column is discussed in the later part of this post.

Height of Structure | Different Levels | Size of Column in mm |

Upto 10 storey | 1 – 10 floors | 700 mm X 700 mm |

Upto 20 storey | 1 – 7 floors | 750 mm X 750 mm |

8 – 14 floors | 600 mm X 600 mm | |

15 – 20 floors | 450 mm X 450 mm | |

Upto 30 storey | 1 – 10 floors | 800 mm X 800 mm |

11 – 20 floors | 650 mm X 650 mm | |

21 – 30 floors | 470 mm X 470 mm |

### Standard minimum size of column and details

Details of minimum size of column that is necessary for any structure based on its height along with other details for column are given below.

**Column details for 1 storey (ground floor) building**

Minimum size of column | 9″ X 9″ (225mm X225mm) |

Main Bars (Main Steel bar dia) | 4 bars of 12mm dia |

Stirrups for shear reinforcement | 8mm dia bars @ 6″ spacing |

Preferred grade of concrete | M20 Concrete (1 : 1.5 : 3) |

**Column details for 2 storey (G+1) building**

Minimum size of column | 9″ X 12″ (225mm X300mm) |

Main Bars (Main Steel bar dia) | 6 bars of 12mm dia |

Stirrups for shear reinforcement | 8mm dia bars @ 6″ spacing |

Preferred grade of concrete | M20 Concrete (1 : 1.5 : 3) |

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**Column details for 3 storey (G+2) building**

Minimum size of column | 12″ X 12″ (300mm X300mm) |

Main Bars (Main Steel bar dia) | 6 bars of 12mm dia |

Stirrups for shear reinforcement | 8mm dia bar @ 6″ spacing |

Preferred grade of concrete | M20 Concrete (1 : 1.5 : 3) |

**Column details for 4 storey (G+3) building**

Minimum size of column | 12″ X 14″ (300mm X350mm) |

Main Bars (Main Steel bar dia) | 4 bars of 16mm dia + 2 bars of 12mm dia |

Stirrups for shear reinforcement | 10mm dia bar @ 6″ spacing |

Preferred grade of concrete | M25 Concrete (1 : 1 : 2) |

### Standard Thumb Rule Used In Construction

Nowadays minimum size of column used in construction irrespective of small building is 9″ X 12″ (225mm X300mm). Recommended grade of concrete for building construction is M20 grade, which is in the ratio of 1 : 1.5 : 3 (1 part of cement and 1.5 part of sand and 3 parts of coarse aggregate with 0.5 parts of water).

**Below is the summary of the standard size of column used in 2021.**

- Column Size – 9″ X 12″ (225mm X300mm)
- Main reinforcement – 6 bars of 12mm dia Fe 500 Steel
- Stirrup rings – T8mm dia bars @ 6″ (150mm) spacing
- Concrete – M20 Grade of concrete (1 : 1.5 : 3)

### Quick Formula For Dimension of Column

A quick method top find the size of column based on the strength of the material and maximum load to be applied on column is given below.

N_{max }= A * f * Reduction Factor

Where,

- N
_{max}= Maximum load that can be applied on column - A = Area of Column in m
^{2} - f = Strength of material in KN/m
^{2} - Reduction Factor = Coefficient for taking into account risk and material variation

## Factors Affecting Column Size

There are many factors that affect the size of column but most important ones are height of the building or structure, distance between columns, alignment of column and many other factors.

**Factors affecting column size are given below:**

- Height of the building or structure
- Distance between adjacent columns
- Load of the structure
- Architectural consideration

Let us look in detail how column size is affected by each factors and what size should be preferred for such situations.

### Height of the structure

As height of the building increases the dead load and live load on the building also increases. To compensate for the increase in load we need to increase the strength of the RCC structure.

As we know that column transfer load from beams and slab to the foundation of the structure of the building. Thus size of column and reinforcement in column is needed to be increased.

### Space Between Adjacent column

Distance between each column in a building should be preferably kept same between centres of 2 column. If columns are placed closer to each other then the size of column can be reduced and vice versa. This space between columns is directly proportional to the size of the column.

Distance between column is directly proportional to column size

For a 9″ X 9″ Column, the maximum distance between the column should not be more than 4 meters. If due to architectural or any other condition distance between column is more than the size of the column is increased.

### Load on the structure

No standard size can be fixed for similar height building as each structure has a different function. As we know to counter the increase in height and dead load of structure, size of column is increased. Similarly for balancing live load, wind load and other loads the size of column is needed to be selected accordingly.

Thus before deciding the size of the column proper load that is going to come on the building should be worked out.

## Column Size Calculation

Size of column shown above for different type of building is minimum standard column sizes for a particular types of buildings. That doesn’t mean that it is to be used everywhere.

Certain type of building condition requires stronger column section. The size of column is mainly dependent on the following factors;

- Concrete grade
- Grade of steel
- Factored load on column

Column size is decided by the following column size formula given by IS 456:2000.

**Pu = 0.4 f _{ck} A_{c }+ 0.67 f_{y} A_{sc}**

Where,

- Pu = Ultimate Load on Column
- f
_{ck}= Characteristics compressive strength of concrete - A
_{c}= Sectional Area of Concrete - f
_{y}= Yield strength of steel - A
_{sc}= Area of Steel Reinforcement - A
_{c}= A_{g}– A_{sc} - A
_{sc}= 0.01 A_{g}(**A**)_{g}= Gross Area of Column - A
_{c}= 0.99 A_{g}

### Example of Column Size Calculation

Let us learn how to design a column to support axial load of 600 KN by using M20 grade of concrete and Fe 500 steel grade.

From the given condition,

Pu = 600 KN,

f_{ck} = 20 N/mm^{2},

f_{y} = 500 N/mm^{2},

Assume,

Steel = 1% and

Factor of Safety = 1.5

**P _{u }= 0.4 f_{ck} A_{c }+ 0.67 f_{y} A_{sc}**

**900 x 10**

^{3}= 0.4 x 20 x (0.99 A_{g}) + 0.67 x 500 x (0.01 A_{g})**A**

_{g}= 79858 mm^{2}For square column,

**Size of Column** = √79858 = 282.59 mm

**Provide square column of size 285 mm x 285 mm**

A_{g} = Provided = 81225 mm^{2}

A_{sc} = 0.01 A_{g} = 0.01 x 81225 = **812.25 mm ^{2}**

Provide** 8 Nos of 12 mm Dia** steel with actual area of steel = **905 mm ^{2}**

The **size of the column** for **600 KN** load is **285 mm x 285 mm** **(12″ x12″)**

## Why No Standard Size Of Column

As you have seen above that the size of column depends upon many factors, thus it would be hard to fixed the size based on these factors.

Size of column depend upon the load to be supported, type of column, distance between column, architectural design, and many other factors affect the size of column. By varying the percentage of steel the size of column can be reduced or increased.

Based on these factors we have to assume the size of column and check for safety of the structure.

### What is Standard Size of Column?

Depend upon the height of the structure and load acting on the structure.

Minimum standard size of column for different height structure are as follows:

Ground floor column size – 9″ X 9″

G+1 Structure column size – 9″ X 12″

G+2 Structure column size – 12″ X 12″

G+3 Structure column size – 12″ X 14″

**What should be the maximum distance between two columns?**

Maximum distance between two column range from 3 to 4 m for small residential building. But for large building with heavy structure it range from 6 m to 9 m.

### What is the standard size of column for 2 storey house?

Standard size of column for 2 storey house is 9″ X 12″

### What is the maximum height of column?

Maximum Height of column can range from 20 m to 24 meter.

### What is the standard size of column for 3 storey house?

Standard size of column for 2 storey house is 12″ X 12″

### What is the standard size of column for 4 storey house?

Standard size of column for 2 storey house is 12″ X 14″

### What is the standard size of column for 5 storey house?

Standard size of column for 2 storey house is 14″ X 14″

### What is the standard size of column for 6 storey house?

Standard size of column for 2 storey house is 16″ X 16″

### Factors affecting distance between two column?

Following are the main factors that decide distance between two column:

1. Total load ( LL + DL ) acting over the column.

2. Type of structural design.

3. Size of the column.

4. Size of the beams resting over the column.

5. Whether the column comes in a seismic zone or not.

6. Type of footing & SBC of soil.

7. No of storeys in the structure.

### Which IS code is used for Column size?

IS 456 : 2000 is used for column.

### How much load can a column take?

Amount of load a column can take is dependent on steel reinforcement and concrete. It is given by,**P _{u }= 0.4 f_{ck} A_{c }+ 0.67 f_{y} A_{sc}**

I am a civil contractor, very informative content regarding building column size. Please write more content related to column and beam designs.