Why so many bricks ???

In my experience , the subject of estimation is quite boring to the students as well as field people.

In that context , we are going through a series of articles devoted to the arithmetic involved in construction.

We have already discussed the estimation of materials in concrete

( Read post : Vow..what a concrete )

Now we shall travel in the masonry today.

If you get bored , just Stop and take a break.

Take a scrap pad and a calculator and do some jugglery yourselves.

That’s how you shall keep aligned .

Re-continue and reflect as many times as you feel.

There is no hurry.

Happy Calculating !

Overview:

We talked about the general aspects of the masonry in the previous post.
We also spoke about  the stone masonry

( Read : Throw the stone..carefully )

Now we shall learn the arithmetic issues involved in counting the bricks.

We shall  be able to find out the :
Number of bricks needed for the masonry work and also the mortar needed for the job.
In other words ,for a given masonry wall we shall be able to compute:

1.No of bricks

2.No of cement bags
3.Sand

And then we can also find out the total material cost.

This shall help us in:
1.Budgeting for materials
2.Ordering the material

Ok ? so all geared up ?
let us begin..here we go:

The Data:
The brick wall which we need to build is 5 m long, 4 m high and it is 200 mm thick.
It is to be jointed in Cement mortar 1:6.
The bricks of size 200 mm x100 mm x 70 mm have been approved.

The method:
1.Calculate the volume of one brick :
0.2m x 0.10m x 0.07m = 0.0014 CuM.
2.Find number of bricks per CuM:
= 1/0.0014 = 714 nos.

So 714 bricks shall be needed if there is no mortar joint. Right ?

3. Now,assume that there is a mortar joint of 10 mm thickness between the  bricks.

So, increase each dimension of brick by 10 mm.

Thus,the volume of each brick with mortar shall be :
0.21 x 0.110 x 0.08 =0.001848 CuM.

4..Again, Find number of bricks per CuM:

= 1/0.0011848  = 541 nos.

5.Thus, number of bricks have reduced from 714 to 541 due to the presence of mortar.

6.Therefore, 714 – 541 = 173 Bricks represent the volume of cement mortar.

173 x 0.0014= 0.2422 CuM.
7.Summary I:

We shall need 541 bricks and 0.24 CuM of cement mortar for 1 CuM of brick work.

8.Now we also need to find out how many cement bags and how much quantity of sand is needed

for 0.24 CuM of mortar .

Let us assume that the mortar quantity is CuM.

The mix is CM 1:6.
We shall use dry mix method.

Cement: [1.52/(1+6)]x 28.8 =  [0.2171]x 28.8 = 6.25 Bags

Sand: [0.2171] x 6  = 1.302  CuM.

Consumption of materials for 1 CuM of cement mortar (1:6):

Cement: 6.25 Bags
Sand:   1.302 CuM.

Now ,we actually need only 0.24 CuM of mortar for 1 CuM of brick work

Hence for 0.24 CuM of mortar , we shall need :
Cement: 6.25 Bags x 0.24 =1.5 bags
Sand:   1.302 CuM. x 0.24= 0.3125 CuM.

9.Summary II:
Consumption of materials for 1 CuM of Brickwork :
Cement: 1.5 bags
Sand:     0.3125 CuM.
Bricks: 541 Bricks

10.Now we are at the final lap:
Volume of brick wall:
5 x 4x 0.2 = 4 CuM

Therefore material consumption shall be:

Cement: 1.5 bags x 4 =  bags
Sand:     0.3125 CuM. x 4 = 1.25 CuM.
Bricks: 541 Bricks x 4 = 2164 Bricks

If the unit rates are known we can also find out total cost of the materials.

11.Assume that :

Bricks : INR 4200 per 1000. [ INR 4.2  per no ]

Sand : INR 4500 per Brass or 100 Cft.

[ INR 45 per cft or 45 x 35.29 = INR 1588 per cuM.]

Cement : INR 300 per bag of 50 Kg.

The material cost shall be as follows :

Cement:  bags@ 300 =       1800
Sand:     1.25 CuM.@ 1588 = 1985
Bricks:  2164 Bricks@ 4.2 =  9088

Total cost :1800 + 1985 + 9088

= INR 12,873

12. Now we can find out the materials cost per CuM  of  brick work :

12,873 /4 = INR 3218.25 per CuM of brick work

or 3218.25/35.29 = INR 91.19 per Cubic feet of brick work

Author’s note :

Hope you have understood the basics.

1.Remember , you don’t have to do all this calculation every .

Just memorize the unit cost i.e INR 3218.25 per CuM or INR 91.19 per Cubic feet of brick work .

As long as the material rates are the same, the cost shall be the same.

2. For those comfortable with spread sheets , once do this calculation in the spread sheet with proper formulae. Later , when any of the variable changes ,the moment you revise that figure, the entire computations shall be automatically revised.

Its really a fun.

believe me.

Happy journey on the path of estimations.

2 thoughts on “Why so many bricks ???”

1. pravin wagh says:

900×450×450 mm brick chamber brick calculate

Like

1. Santosh Kulkarni says:

Yogesh
Great to see this.