How You Can Easily Calculate The Number of Concrete Blocks in a Wall

Concrete blocks have become an integral part of all modern structures. The use of concrete blocks has made it easier to build mammoth structures within a short period. Furthermore, concrete blocks have promised more reliable, durable, and rigid structures. Concrete blocks are more affordable than traditional red bricks. It is an excellent choice for constructing walls for foundations or utility buildings.

There are numerous types of concrete blocks available for different construction purposes. Concrete blocks are commonly known as CMU or concrete masonry units. They come in different shapes and sizes as well. It is essential to calculate how many concrete blocks you require before starting construction. Knowing beforehand can save you from extra costs and increase efficiency in the construction work. Furthermore, you do not have to appoint an expert to calculate the number of concrete blocks required for your work. You can do it easily by simply doing some math with a pen and paper.

How to Calculate the Number of Concrete Blocks

There are many ways you can calculate the number of concrete blocks you might require for building a wall or other parts of the project. From all these methods, two are very simple to understand and apply. These are:

1.   Surface Area Calculation Method
2.   Volume Calculation Method

How to Calculate the Number of Concrete Blocks Using Surface Area Calculation Method

To perform this method, you need to collect some data first. You need to know the wall’s surface area that you intend to build, the surface area of a standard concrete block that you want to use, and the surface area of any opening in the wall, e.g., windows doors. The following steps will guide you:

Step 1

First, you need to determine the height and length of the wall you want to build. Generally, the height is around 10 feet, and the length will depend on how long you want. For ease of calculation, let’s assume the length is 10 feet.

Step 2

After calculating the height and length, now it’s time to figure out the wall’s surface area. It can be determined using a simple formula, Surface Area = Length * Height.

For our example, the surface area of the wall becomes:

• Surface Area = 10 * 10 = 100 square feet.

Step 3

If you plan to place any windows or doors in the wall, you need to subtract its surface area from the total surface area of the wall. Let’s assume you plan to place a window that measures 5 feet in length and 5 feet in height. So, the surface area of the window becomes:

• Surface Area of the Window = 5 * 5 = 25 square feet.

Step 4

Now, you need to subtract the window’s surface area from the total area you calculate in step 2. For our case, it becomes:

• Final Surface Area of the Wall = 100 – 25 = 75 square feet

Step 5

At this stage, we have calculated everything about the wall. We need to figure out what kind and what size of concrete block you want to use in the wall. Let’s assume the measurement of a standard-sized concrete block.

• Block Measurement        = 16” * 8” * 8” (measurements are in inch)
• Mortar Allowance            = 1”
• Total Surface Area of One Block with Mortar  = (16+1) * (8+1) = 153 square inch.

                                                                                              = 153 / (12 * 12) (1 feet = 12 inch)                                                        

                                                                                              = 1.0625 square feet

Step 6

This is the final step of your calculation. You need to divide the total surface area of the wall by the surface area of one block to calculate the number of concrete blocks.

Number of Blocks = Final Surface Area of the Wall / Total Surface Area of One Block = 75 / 1.0625 = 71 blocks

However, it would help if you considered wastage as many blocks can get damaged due to transportation, poor handling, or other reasons. Considering a 5% wastage should be more than enough. So, for our example:

• Total Number of Blocks = 71 + (71 * 5 / 100) = 71 + 4 = 75 blocks

By following these six steps, you can easily calculate the number of concrete blocks required to construct a wall.

Source: Daily Civil

How to Calculate the Number of Concrete Blocks Using Volume Calculation Method

Like the surface calculation method, you need some data about the volume of the wall, the volume of the concrete block, and the volume of the openings in the wall. The following steps can be followed to calculate the number of concrete blocks.

Step 1

In volume calculation, you need a third parameter to determine the volume. You need to determine the wall’s length, height, and thickness for this measurement. Taking our previous example, we get

• Length       = 10 feet
• Height        = 10 feet
• Thickness  = 8” = 0.67 feet     (thickness of the wall is comparable to the thickness of the concrete block)

Step 2

Now, you can calculate the volume of the wall by using the following formula

• Volume = length * Height * Thickness
• So, volume of the wall = 10 * 10 * 0.67 = 67 cubic feet

Step 3

If you plan to place any doors or windows, you need to subtract the volume of that opening from the wall area.

Taking our previous measurement, we get

The volume of the window = 5 * 5 * 0.67 = 17 cubic feet (thickness of the window is comparable to the thickness of the concrete block)

Step 4

Now, you can subtract the amount.

• Final Volume of the Wall = 67 – 17 = 50 cubic feet

Step 5

Now, you need to calculate the volume of a single concrete block with a mortar allowance.

If the block is of the same size as in the previous case and mortar allowance is 1 inch, we get

Volume of a Single Block with Mortar = (16 + 1) * (8+1) * 8 = 1224 cubic inch

                                                                     = 1224 / 12 * 12 * 12 = 0.70 cubic feet

Step 6

• Number of Blocks = Final Volume of Wall / Volume of a Block with Mortar = 50 / 0.70 = 71 blocks
• Considering 5% wastage of blocks like the previous case will increase the number.
• Total Number of Blocks = 71 + (71 * 5 / 100) = 71 + 4 = 75 blocks

Summary

Calculating the number of concrete blocks on a wall beforehand can help you reduce cost and increase efficiency. Suppose the wall is already constructed, and for some reason, you need to calculate the number of concrete blocks on that wall. In that case, you can count the number of blocks individually or follow the discussed method, which is much easier. Without any engineering or architect skills, anyone can figure out the number of blocks required for a project. However, you should keep in mind that blocks are not abstract unit areas. Concrete blocks are physical objects. If you get fractional results, do not get confused. You should take the higher integer number in such cases.

Frequently Asked Questions (FAQs)

Do I need the help of experts to calculate the number of required blocks in a wall?

Ans: No. Anyone can figure it out by following simple steps of arithmetic.

What size is a concrete block?

Ans: In Bangladesh, Concrete blocks come in a different range of shapes and sizes. They can also be custom-made. So, the size will depend on the category you select.

How to measure the length of a wall?

Ans: You can measure any length by using tape measures.

How are concrete blocks priced?

Ans: Concrete blocks are priced per block or meter square.