How To Estimate Numbers Of Blocks Required For Your Building Project From A Simple Plan Layout

Fig 1.1 Ground Floor Plan of a Room

It’s natural for one to wonder how many blocks are in a wall. 

The simplest and surest way to obtain that number is to count them all, but that could take a long time, and it isn’t of any help for someone who wants to know how many blocks are needed to build a wall.

Fortunately, basic arithmetic can be used to calculate a fairly reliable estimate to satisfy curiosity as well as practicality. Does this Spark an idea?

In this article, I will unveil to you the secret on how to estimate on your own from a building plan layout, the number of blocks that would be consumed in a building construction.
For this particular lesson, we are going to use the plan layout above (fig 1.1) as our case study.

NOTE:
• The nature of the soil for this project is a very good and stable soil.
• The type of foundation used is a strip foundation.
• 9 inches blocks will be used in the foundation since its stable.
• 6 inches blocks will be used after the floor slab (DPC) to roof level.
• The length of a block ( 6inches or 9inches is 450mm ) = 0.450m = 1.476ft

The width of 6 inches blocks is 150mm = 0.150m = 0.492ft
• The width of 9 inches block is 225mm = 0.225m = 0.738ft
mm = millimeters
m = meters
‘’ = inches
‘ = feet
   = approximately
m3 = cubic meter.

Generally the blocks laid from foundation to DPC level is 4 courses/levels, from DPC to the base of window is another 4 courses, from base of window to lintel is 5 courses, after your lintel, there will be another 2 courses followed by your roof beam. Which will make a total of 15 courses.

After digesting this, it will give you an edge to checkmate your building Engineer on the request for bags of cements for your building project.

Now with these parameters above let’s calculate the 9 inches blocks that will be laid in the foundation

From the building plan above (fig. 1.1 ) The total length of the foundation trench is :
16’0’’+13’0’’+16’0’’+13’0’’ which is 16ft+13ft+16ft+13ft = 58ft =17.6784m  17.68m
Calculating the required number of standard construction blocks:
Below provides a very fast, simple way to find the answer.
Length: To calculate the number of construction blocks by a specific length:

Multiply the height by 1.5
Example: 8 ft. x 1.5 = 12 rows (includes the mortar joints)
Area: To calculate the number of construction blocks by a specific area:
Multiply by 1.125
Example: 160 Sq. Ft. x 1.125 = 180 blocks (includes the mortar joint)

NOTE: These measurements are for a general guideline only..

From the table above the number of 9 inches blocks needed for the foundation wall will be:
58ft x 0.75 = 43.5  44 blocks
Since the foundation would be 4 courses, we will have:
44 blocks x 4 courses = 176 blocks.
So therefore, the foundation will take 176 blocks (9 inches).

USING AREA METHOD
Length of foundation wall = 58ft
Height of foundation wall = 3.018ft
Area of foundation wall = 58ft x 3.018ft = 175.0656 sq ft
To get the numbers of blocks we will multiply by 1.125(look up table 1.1)
i.e = 175.0656 sq ft x 1.125 = 196.9  197 blocks

Furthermore, from the DPC to the roof level excluding lintel and roof beam, we have a total of 11 courses.

The numbers of blocks will be: 44 blocks x 11 courses = 484 blocks (6 inches) neglecting window and door openings

USING AREA METHOD
Length of block wall = 58ft
Height of structure excluding lintel and roof beams = 8.3005ft
Area of entire block structure = 58ft x 8.3005ft = 481.43 sq ft

To get the numbers of blocks we will multiply by 1.125(look up table 1.1)
i.e 481.34 sq ft x 1.125 = 541.5075  542 blocks

Now we need to consider the windows and doors in the plan layout, taking into consideration that the height for windows and doors is 4ft and 7ft respectively.
From the plan, we have:
• 3 windows of 5ft by 4ft and
• 1 door of 3ft by 7ft

AREA OF WINDOW
5ft x 4ft = 20 sq ft
To get the numbers of blocks we will multiply by 1.125(look up table 1.1)
i.e 20 sq ft x 1.125 = 22.5  23 blocks
For 3 windows it will be 23 blocks x 3 = 69 blocks
Therefore the 3 window will take approximately 69 blocks

AREA OF DOOR
3ft x 7ft = 21 sq ft
To get the numbers of blocks, we will multiply by 1.125 (look up table 1.1)
i.e 21 sq ft x 1.125 = 23.625  24 blocks

Total blocks in window and door area will be:
69 blocks + 24 blocks = 93 blocks
Therefore the number of 6 inches blocks from DPC to roof level will be
484 blocks – 93 blocks = 391 blocks

So therefore the total number of blocks needed from foundation to roof level is:
197 blocks (from foundation wall) + 391 blocks (from DPC to roof)
= 588 blocks

NOTE:
The difference in blocks between the first method and the area method may be due to mortar space not considered.
This difference will be accounted as wastages due to breakage, since calculations are not 100% true.

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