HOW TO CALCULATE NUMBER OF CONCRETE BLOCKS IN A WALL

There are several methods for calculating number of blocks in a wall. In this article, I will explain two simple methods to find out total no. of blocks for a wall.

*Surface area method.
*Volume method.

CONCENTRATION PLEASE

PROCEDURE:

A. CALCULATION BY SURFACE AREA METHOD:
REQUIRED DATA:

1. Surface area of the wall.

2. Surface area of a standard concrete block.

3. Surface area of openings in the wall.

STEP 1:
Determine The Length & Height Of The Wall:

Let,

the Length of the wall = 10 feet.

The height of the wall = 10 feet.

STEP 2:
Calculate The Surface Area Of The Wall:

We know, 

Surface Area = Length × Height

∴ Surface area of the wall = 10×10 = 100 sq. feet.

STEP 3:
Calculate The Surface Area Of Openings:

If the wall has any openings such as door, windows etc, calculate the surface area of openings.

Let, 

The wall has a window of: 

3′×3′

∴ Surface area of the window = 3×3 =9 sq. ft

STEP 4:
Substract The Surface Area Of Openings From Surface Area Of Walls:

∴ Final Surface Area of wall = 100 – 9 = 91 sq.ft.

STEP 5:
Calculate The Surface Area Of A Concrete Block With Mortar Allowance:

Let,

 The block is 

16″×8″×8″ and mortar allowance is 1″

∴ Surface Area of one block with mortar = 

(16+1)(8+1)= 153 inch² = 153/12×12 = 1.0625 sq.ft

STEP 6:
Divide The Total Surface Area Of The Wall By Surface Area Of One Block:

∴ Number of blocks = 

Surface Area of wall/Surface Area of a block = 

91/1.0625 = 86

Consider 5% wastage of concrete blocks.

So 

The total numbers of blocks required=

86+(86×5/100) = 86+4 = 90.

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B. CALCULATION BY VOLUME METHOD:
REQUIRED DATA:

1. Volume of the wall.

2. Volume of a standard concrete block.

3. Volume of openings in the wall.

STEP 1:

Determine The Width, Height, And Thickness Of The Wall:

Let,

The width of the wall = 10 feet.

The height of the wall = 10 feet.

The thickness of the wall = 8″ = 0.67 feet. [ Thickness of wall will be same as the thickness of one concrete block]

STEP 2:

Calculate The Volume Of The Wall:
We know,

Volume = Width×Height×Thickness

∴ Volume of the wall = 10×10×0.67 = 67 ft³.

STEP 3:

Calculate The Volume Of Openings:

If the wall has any openings such as door, windows etc, calculate the volume of openings

Let,

The wall has a window of 3′×3′×0.67′ cu.ft

∴ Volume of the window = 3×3×0.67 =6 cu. ft

STEP 4:

Substract The Volume Of Openings From Volume Of Walls:

∴ Final volume of wall = 67 – 6 = 61 cu.ft.

STEP 5:

Calculate The Volume Of A Concrete Block With Mortar Allowance:

Let,

The block is 16″×8″×8″ and mortar allowance is 1″

∴ Volume of one block with mortar = (16+1)(8+1)8 = 1224 cu. inch [The mortal will be given on the upper side and one side of every concrete block]

= 1224/12×12×12 = 0.70 cu.ft

STEP 6:

Divide The Total Volume Of The Wall By Volume Of One Block:

∴ Number of blocks = 

Volume of wall/Volume of a block = 

61/0.70 = 86

Consider 5% wastage of concrete blocks.

So

The total numbers of blocks required = 

86+(86×5/100) = 86 + 4 = 90.

Note:

If the wall does not have any opening skip step 4, and just divide the surface area of wall by the surface area of one block.