How to Calculate the No. Of concrete Blocks?

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How to Calculate the No. Of concrete Blocks?

Engineering Geeks March 22, 2022

 How to Calculate the No. Of Concrete Blocks

The availability of concrete blocks is in different sizes and shapes and has different physical properties. They may be hollow or full, made from light cement or very dense aggregates.

The calculation of no. of concrete blocks is very simple for a building; either residential or commercial & requires no prior information of building and architecture.

There are different methods for calculating the no. of blocks in a wall.
 

 


1)   Surface Area Method 

Data Required

1-    Surface area of wall.

2-    Surface area of standard concrete block.

3-    Surface area of openings in wall.

 

Step A-

 

Let us consider, Length of wall be 12 feet

                            Height of wall be 14 feet.

 

Step B-

     Calculating Surface Area of Wall-

                 <Surface Area = Length * Height>

Surface area of Wall

       = 12 * 14

          = 168 sq. feet.

Step C-

 

Calculate the Openings Surface Area-

If the wall has many openings such as door, windows etc.

                    Calculate the openings surface area

 1)   Let the wall has 2 windows of 4′ * 3′     (as shown in picture)

          Surface area of the window = 2 * 4 * 3 = 24 sq. ft.

 

2)   Let the wall has a door of 7′ * 3′              (as shown in picture)

 

          Surface area of the door = 7 * 3 = 21 sq. ft. 


                             Step D-

 Subtract Openings Surface Area from Surface Area of Wall,

   I.e.

     Final Surface Area of wall

      = 168 – (24+21)

      = 123 sq. ft.

STEP F-

Now, calculating the Surface Area of Concrete Block with Mortar Allowance-

                 (As shown in picture)

 

 

Let us consider, the block be 15″ * 8″ * 8″ and mortar allowance is 1″

∴ Surface Area of one Concrete block with mortar

        = length * height

        = (15+1) * (8+1)

= 144 inch²

               Now in Square Feet

                   = 144 / (12 * 12)

                    = 1 sq. ft.

Step G-

 

Now, Number of blocks = Surface Area of the wall / Surface Area of the block

                                        = 123 / 1

                                        = 123

Let us Consider 5% wastage of concrete blocks.

So total numbers of blocks = 123 + (123 * 5/100)

                                           = 123 + 6.15

                                             = 129.15

     Numbers of blocks           = 130

       2. Volume Method

Data Required

 

1-      Volume of the wall.

2-      Volume of a standard concrete block

3-      Volume of openings in wall

 

Step A-

 

Let us consider,

Length of the wall = 12 feet.

Height of the wall = 14 feet.

Thickness of wall = 8″ = 0.67 feet.

         <Remember Thickness of wall will be same as the thickness of one concrete block>

 

Step B-

 

Now, Calculate Volume Of Wall:

                               Volume = Length * Height * Thickness

                               ∴ Volume = 12 * 14 * 0.67

                          ∴ Volume = 112.56 cubic feet

 

Step C-

 

Now the Volume of Openings,

If the wall has many openings such as door, windows etc.

Then the volume of openings will be calculated.

 

Let us consider, the wall has Two windows of 4′ * 3′ * 0.67′

        <Remember thickness of window = thickness of the wall] 

∴ Volume of the window = 2*4 * 3 * 0.67

                                          =16.08 cu. ft.

Also, Door Volume having dimensions = 7′ * 3′

  Volume of the Door = 7 *3 * 0.67

       <Remember thickness of window = thickness of the wall] 

 ∴ Volume of the Door = 14.07




Step D-

Subtract the Volumes

∴ Final volume of wall 

                = 113 – (16.08 + 14.07)

                = 82.41 cu. ft.


Step E- 

    Now Calculate the Volume of Concrete Block having Mortar Allowance

Let the dimensions block be 15″ * 8″ * 8″ and mortar allowance is 1″

∴, 

   Volume of one block with mortar

             = (15+1) * (8+1) * 8

               = 1152 inch 3

 

[Mortal will be given on the upper side of wall and one side of every concrete block] 

                          Volume in cubic feet = 1152 / (12*12*12)

             = 0.670 cu. Ft.

Step F-

      Now total Number of blocks = Volume of wall/Volume of a block

                                                       = 82.41 / 0.670

                                                       = 123

Also, Consider 5% wastage of blocks.

..., Total number of blocks required = 123 + (123 * 5/100)

                                                              = 123 + 6.15

Total number of blocks                  = 129.15   =  130

         Numbers of blocks           = 130

Note:

It means that either the calculation can be calculated by Surface Area Method or Volume method, getting the same results.

Also, if the wall does not have any openings, then skip the step 4, and just divide the surface area of wall by surface area of one block.


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