How To Calculate The Numbers Of Blocks And Cements Needed To Build Your House.
Building a house is the dream of most Nigerians both home and abroad, and one of the fundamental challenges majority of these people are faced with is planning ahead and knowing the quantity of various materials that would be needed to put their dream house to reality. This thread would be dedicated to treating extensively a DIY approach on HOW TO CALCULATE THE NUMBERS OF BLOCKS AND CEMENTS NEEDED TO BUILD YOUR HOUSE.

This DIY(Do It Yourself) approach is not aimed at stopping you from hiring a professional to have a perfect work done, but just to give you an insight on how individual professionals arrives at concluding numbers of quantity of materials required or requested for. This will also help you to know when a particular Engineer, Architect, Builder, Manson, etc are been realistic and not only trying to rip you off your hard earn money.
NB: This is just an eyes opening thread. You might eventually need the help of a professional at the long run for more complex aspects that can’t be treated on this thread.
The First section would be dealing with the block aspect and the numbers of contribution from people and their interest would show how soon the cement aspect would be treated.
We have different types of blocks in vogue in Nigeria and in diverse sizes. We have the solid block (no hole in-between) and we equally have the hollow blocks(the common type you get from block industries in Nigeria with holes in between).
They come in various sizes, 4” or 4inches, 6” or 6inches, 9” or 9inches. We would be treating extensively the 6inches and 9inches because they are in vogue and are majorly used as partitioning walls and external walls respectively. This thread won’t be breaking down the use or importance of individual types of block and sizes but only aimed at addressing quantity.
What does 9”, 6”, and 4” means?
The only physical difference seen in the above sizes of blocks is in their thickness. From experience, the 4”, 6”, and 9” blocks have the same height, and same length.
Check The Free Hand Sketch Picture Below To Get An Idea Of What Am Talking About

Picture 1.

In this approach, we would be using two DIY methods in tackling the question of how many blocks, etc. A sample floor plan would also be used as a guide to helping us understand the smallest bit of the calculation.
The first Approach is the Square Meter Method and the second is the Length in Meter Approach.
Since all architectural and structural drawings would come in meters and millimetres, which are the standards in Nigeria, this study would also be done in meters(m) and millimetres(mm).
NB: 1,000mm = 1m : 3m = 3,000mm
Also note, the size of block be it 4”, 6” or 9” has nothing to do with the quantity that would be needed.

EngrOYemi:
In this approach, we would be using two DIY methods in tackling the question of how many blocks, etc. A sample floor plan would also be used as a guide to helping us understand the smallest bit of the calculation.
The first Approach is the Square Meter Method and the second is the Length in Meter Approach.
Since all architectural and structural drawings would come in meters and millimetres, which are the standards in Nigeria, this study would also be done in meters(m) and millimetres(mm).
NB: 1,000mm = 1m : 3m = 3,000mm
Also note, the size of block be it 4”, 6” or 9” has nothing to do with the quantity that would be needed.

I have taken my seat in the classroom.Let the lecture begin,please.Thanks

Square Meter Methods:

Since the important aspect for calculating numbers of blocks is the height and length:
From the diagram in Picture 2, Note:
Height of Block = 225mm = 0.225m
Length of Block = 450mm = 0.450m
Remember Area = L x B (from picture 2, check out the stretcher face, bond and bed):
Total Length = 0.45m + bonding thickness(0.025m) = 0.475m
Total Height = 0.225m + bed thickness(0.025m) = 0.25m
Area = 0.475mX 0.25m = 0.1186 = 0.12sqm
Note as our Constant K. : (One Block = 0.12sqm)

Please note, use 0.1186sqm(don't round it up) if big project is involved (Why would you even want to do all these yourself if bigger project is involved?).

Example 1.
If a proposed wall is 8m long and 3m high. Calculate the numbers of blocks needed to complete the project.
Solution:
Lenght of Wall = 8m
Height of Wall = 3m
: The area of the wall = 8m X 3m = 24sqm.
Recall since 1 Block = 0.12sqm
To know the numbers of blocks for 24Sqm = 24Sqm/0.12sqm = 200blocks.
Considering 10% for cuttings and breakages
10% of 200blocks = 20Blocks
Total numbers of Blocks = 200 + 20 = 220 blocks.
Answer = 220Blocks.

kinzodigital:


I have taken my seat in the classroom.Let the lecture begin,please.Thanks

Thank you for following us.

Example 2.
A rectangular piece of land with length 30meters and breath 16meters is to be fenced. Calculate the numbers of blocks needed if the proposed height of the fence is 2.5meters.
Solution:
Note that a rectangle has 4 sides.
Remember the two opposite sides are equal.
Total Length = 2L + 2B = 2 X 30m + 2 X 16m
= 60m + 32m = 92m
Height of the fence = 2.5m (from the question).
: Area = 92m X 2.5m = 230Sqm (recall area of a wall = L X H)
Nos of blocks = 230/0.12(recall the area of a block = 0.12sqm) = 1,917 blocks.
Considering 10% for cuttings and breakages:
10% of 1,917blocks = 192blocks.
Total Blocks needed for the fencing = 1917 + 192 = 2,109bl0cks.
Answer = 2,109Blocks.

Seat booked

How many blocks will be needed to fence 1 acre of land?

Real14all:
How many blocks will be needed to fence 1 acre of land?

Telling you a particular number of blocks would fence your 1acre of land is like prescribing drugs to patient without consultation or test.
If you have your survey plan with you, kindly share for your estimated number of blocks.
Thanks.

Adejunwonlo94:
Seat booked

Nice one

Hello Everyone!
Before we continue in this expository lecture, permit me to acknowledge the presence of all the professionals in the built environment.
I respect all the Engineers, Architects, Builders, Quantity Surveyors, Land Surveyors, Building Contractors, Estate Valuers & Developers, Technicians, Artisans, Dealers/Sellers of building materials, all Directors and CEOs, Lawyers & professionals in other sectors, and everyone here present and active on nairaland.
Your sincere and constructive contributions for enlightenment of everyone would be well appreciated and help us go far.

Thanks.

Thanks for the info. Engryemi.
My question is, is it the same size of 0.12sqm calculated for 9" also for 6" and 4" blocks?

Kala11:
Thanks for the info. Engryemi.
My question is, is it the same size of 0.12sqm calculated for 9" also for 6" and 4" blocks?

Yes you're right.
I noted that all the 3 sizes of blocks mentioned above have the same height and length, the only physical differences is in their thickness. We arrived at the 0.12sqm by also putting to consideration the bed and the bond.
Kindly refer to Picture 1. For better clarification.

If there is anyone who might want us to use his/her sample floor plan (well detailed floor plan) to calculate the number of blocks needed for the project completion, it would b welcomed. But in the absence of none, I would upload the floor plan of one of my clients(a very simple floor plan) so we can digest it well.
NB: The benefits attached to using you floor plan are numerous. You have idea of numbers of blocks, quantity of cements depending on grades of concrete, quantity of tiles, quantity of paints, cost of doors & windows, and if time permits, the cost of roofing, etc. Early birds.

I awaits any before I take the next step...Thanks.

A Sample Ground Floor Plan is here attached as a case study for a thorough breakdown of all we have been discussing here.
Picture 4.

I hope this uploaded ground floor plan is clear enough and we are good to go to for the next stage.

OPENINGS
Now before we go further, let us deal extensively on the openings. The common openings that would be treated here and put to consideration are the doors, windows and maybe arc openings. All openings are meant to be deducted from the total number of blocks required.

DOORS
Note that we have different sizes of doors which are majorly a factor of their purpose or function. It's obvious that entrance doors, exit doors, bedroom doors, bathroom doors, etc. have different sizes(wideness) but most times exhibits/have same heights of 2100mm or 2.1m.
Various Door Types By Their Local/Standard Name, Sizes/Dimensions and Their Square Meter (Sqm).

2 1/2ft Door = 750mm X 2100mm = 1.6sqm
3ft Door = 900mm by 2100mm = 1.9sqm.
4ft Door = 1200mm by 2100mm = 2.5sqm.
5ft Door = 1500mm by 2100mm = 3.2sqm.
6ft Door = 1800mm by 2100mm = 3.8sqm.

Note: Not all doors have the height of 2100mm/2.1m. Some doors have specs higher than that.

WINDOWS
This section will not be dealing with types of window in the context of material makeup or system of opening like sliding, casement etc. but would be addressing sizes of various windows in vogue and their sqm.

Some Window Sizes
400mm by 400mm = 0.16sqm
600mm by 400mm = 0.24sqm
600mm by 600mm = 0.36sqm
1200mm by 1200mm = 1.44sqm
1200mm by 1500mm = 2.25sqm
1500mm by 1800mm = 2.7sqm
Etc.

Having an assumption that we all now understand the basic things needed to be known when calculating the numbers of blocks, I will now break down the ground floor plan uploaded above.

Solution To The Ground Floor Plan Above.
To make the explanations easier, we would be using the grid lines to tackle the problems above.
From the floor plan, we have our grid lines from 1-10 and also from A-E.

Horizontal Grids
Grid 10 – Grid 10
Distance of walls in Grid 10 = 7,200mm = 7.2m
Grid 9 = 7,200mm = 7.2m
Grid 8 = 2,063mm + 3450mm = 5513mm = 5.5m
Grid 7 = 2,063mm = 2.1m
Grid 6 = 2,063mm + 3450mm = 5513mm = 5.5m
Grid 5 = 3,300mm = 3.3m
Grid 4 = 3,300 = 3.3m
Grid 3 = 3,450mm = 3.5m
Grid 2 = 3450mm = 3.5m
Grid 1 = columns
Total Length of horizontal grid = 41.1m

Vertical Grids :
Grid A = 15775mm = 15.8m
Grid B = 4950mm = 5m
Grid C = 13225mm = 13.2m
Grid D = 1200mm = 1.2m
Grid E = 14998 = 15m
Total Lengths of Vertical Grids = 50.2m

Total lengths of vertical and Horizontal grids = 41.1m + 50.2m = 91.3m

The next thing I would have loved to do is to upload the windows and doors schedule so we can know easily how many openings we have and deduct them from the total walls. This I would upload but won't really be useful since the schedule addresses all the windows and doors both on the ground and upper floor. The purpose of uploading the schedule is just to get us familiar with some of this architectural drawing sections.
You can also follow this link to read about the various drawings needed for building approval to get yourself familiar with so many other things:
https://www.nairaland.com/4485423/various-drawings-needed-building-approval

NB: A complete architectural drawing must also have door, and window schedule etc.
Below is a sample window and door schedule. Take your time to study the uploaded schedule well.
Keep abreast of the next stage as I will be back soon.

Since we know the total length of all the walls already, therefore it's important to know the Total Area :

The average height of most floors (levels) of building is 3m. But for this context, we are using the height of 3.45m.
Recall Area = L X B = L X H
: Since the L = 91.3m and H = 3.45m
: The Total Area of wall = 91.3m X 3.45m
= 314.985Sqm = 315sqm.

At this stage, we will make some assumptions. Some people called complaining that the floor plan is not so clear and to read the dimensions was challenging. I guess the image was too heavy and the quality was altered by nairaland server.
Let’s assume we have 12 big windows with the dimension 1200mm by 1500mm, 5 Small Toilet windows with dimensions 600mm by 600mm, and 10 doors assuming all the doors have the dimension of 900mm by 2100mm.
Big Window = 1200mm X 1500mm = 1.2m X 1.5m = 1.8sqm
Total Sqm of big windows = 1.8m X 12 = 21.6Sqm
Small windows = 600mm X 600mm = 0.36sqm
Total Sqm of small windows = 0.36m X 5 = 1.8sqm
Doors = 900mm X 2100mm = 1.89Sqm
Total Sqm of Doors = 1.89m X 10 = 18.9sqm
Total Sqm of openings = 21.6sqm + 1.8Ssqm + 18.9sqm = 42.3sqm
Total Sqm of block area = Area of Total Wall – Openings
= 315sqm – 42.3sqm = 272.7 = 273Sqm.
Numbers of blocks = 273/0.12(area of a block) = 2,275Blocks.
Add 10% for cuttings and breakages = 2275 + 228 = 2503 Blocks.
Answer = 2503 Blocks

Remember to use same method to calculate for the numbers of blocks for Strip Foundation but if your Foundation Design type is raft, no need.

Note:
This was put together as an attempt to help artisans, students in technical colleges, polytechnics and universities, fresh graduates, prospective house owners, contractors etc. who are been faced with the challenges of quantity of blocks amidst other challenges in the built environment to get it tackled with a step by step approach.
This is not an attempt to encourage individuals not to patronise professional cost personnel (Q.S) who will do better justice when big/massive project is to be put in place. You can save yourself a whole lot of guess work, time and stress when you get a qualified person to do it right. Remember No Knowledge Is Wasted.
Drop your questions here or reach us via the details on our signature and we promise to be responsive enough to tackle all your questions within our professional scope.

We promise to go through this course considering two methods. The method above is the comprehensive and detailed method known as the the Square Meter Method. I decided to take us through this method first before I teach us the cheat method which is also a very easier and short method.