How To Calculate How Many Blocks You Need To Complete Your Bungalow
Good Day All....
Often times I get people asking me this question "HOW MANY BLOCKS WOULD I NEED TO COMPLETE THIS BUILDING" immediately after handing their design to them; I do not think it's bad to plan and budget but I always encourage they start and not let the fear of the unknown kill the dream.
Today, I would be breaking it down so you can actually calculate this quantities yourself...... but, we need a plan to work with (I have attached a simple plan & elevation for this purpose).
FOR THE PURPOSE OF THIS CALCULATION WE WOULD BE USING THE STANDARD FORM OF ARCHITECTURAL MEASUREMENT; THE MILLIMETER (mm)
DESIGN:- A GATE HOUSE.
Lets use the attached simple gatehouse design with one 900mm x 2100mm door, a 1200mm x1200mm window and a 600mm x 600mm toilet window plus a 750mm x 2100mm toilet door. (I have done the elevation to ensure all possible elements are visible on the elevation).
OK - This is it.
Our 1st task would be to find the linear length of the entire building line i.e. how long is the block if we put them in a single line; we would achieve this easily by taking one grid-line after the other.
Grid 1 = The linear length of blocks on grid-1 is 4500mm (it’s that simple), now let’s take for others.
Grid 2 = 4500mm also (now you'll notice i omitted the windows and door opening on grid-2, we would come back to deduct those.
Grid A = 3000mm
Grid B = 3000mm
Grid C = 3000mm
Now, lets add to get the total linear length of building = (4500x2) + (3000x3) = 18,000mm [it’s important to group similar dimension especially when dealing with larger drawings to safe time].
Now that we have the linear length remember the block works are divided into 2. The Foundation Blocks (Sub-Structure) and The Building Blocks (Super-Structure)
NOTE: The length of a standard block (in Nigeria) is 450mm and the height is 225mm for both 6" and 9" blocks....
A. BLOCKS NEEDED FOR FOUNDATION
Question: How many courses of blocks are you planning for your foundation? I would use 4 courses for this calculation.
Number of Blocks needed per course of block = [TOTAL LINEAR LENGTH / LENGTH OF BLOCK] = [18,000 / 450] = 40 blocks per course but remember I'm using 4 courses hence; TOTAL BLOCKS NEEDED TO COMPLETE THE FOUNDATION = 40 blocks x 4 courses = 160 blocks (whether 6" or 9"
Note: We didnt need to deduct for openings, obviously in the foundation - we have none. (If your design has a foundation drawing, then use the foundation drawings to calculate the nos of blocks needed for in the foundation and the ground floor plan for the super-structure quantities)
B. BLOCKS NEEDED TO ROOF LEVEL
Question: What is the height of the structure I'm building? In this design I have used a building height of 2700mm; this means that the number of courses I'll have would be = [HEIGHT OF STRUCTURE / HEIGHT OF 1 BLOCK] = [2700 / 225] = 12 courses of blocks.
Number of Blocks needed per course of block = [TOTAL LINEAR LENGTH / LENGTH OF BLOCK] = [18,000 / 450] = 40 blocks per course but here we have 12 courses of blocks to go. (If you plan to tie your lintel all-round the structure because it’s a small one, then minus 1 course taken by the lintel and use 11 courses BUT I don't advice that, so I'll use 12 courses and use my lintels only over opening), so;
TOTAL BLOCKS NEEDED TO COMPLETE THE WALLS = 40 blocks x 12 courses = 480 blocks (whether 6" or 9"
B(ii). DEDUCT OPENINGS IN B ABOVE
Opening in drawing:
a. 750mm x 2100mm
b. 900mm x 2100mm
c. 600mm x 600mm
d. 1200mm x 1200mm
There are no half blocks, so every numbers would be rounded to the nearest whole number.
a. 750x2100 {where 2100 is the height of door; see elevation}
Nos of blocks needed per course = 750 / 450 = 1.6667 = 2 blocks
Nos of courses in door = 2100 / 225 = 9.3333 = 10 courses
Number of blocks in 750x2100mm door = 2 x 10 = 20 blocks.
b. 900x2100.
Nos of block needed by course = 900 / 450 = 2 blocks
Nos of courses = 2100 / 225 = 9.3333 = 10 courses
Number of blocks in 900x2100 door = 2 x 10 = 20 blocks
c. 600x600 {where 600mm is the height of window}
Nos of blocks needed per course = 600 / 450 = 1.333 = 2 blocks
Nos of courses in door = 600 / 225 = 2.6667 = 3 courses
Number of blocks in 600x600mm window = 2 x 3 = 6 blocks.
d. 1200x1200 {where 1200mm is the height of window}
Nos of blocks needed per course = 1200 / 450 = 2.6667 = 3 blocks
Nos of courses in door = 1200 / 225 = 5.333 = 6 courses
Number of blocks in 1200x1200mm window = 3 x 6 = 18 blocks.
TOTAL BLOCKS CALCULATED INTO OPENINGS (in this design) = 20+20+6+18 = 64 blocks
Now let’s deduct B(ii) from B = 480 blocks - 64 blocks = 416 BLOCKS NEEDED
TOTAL BLOCKS NEEDED TO BUILD THE STRUCTURE (Foundation + Main building) = 160 + 416 = 576 Blocks.
But we should consider waste and broken blocks right? - Lets add 10% for waste and broken blocks = 576 + 58 = 634 blocks.
IMPORTANCE OF THIS CALCULATION:
You could use this calculation to:
i) Calculate how much you would spend on blocks by multiplying quantities above by the price of 1 block.
ii) You could also use it to estimate approximately, how many bags of cement would complete the block-works
iii) You could use it to negotiate and have an idea of how much to pay the bricklayer
iv) Plan your budget
Thanks for following; please feel free to ask your questions or share your reservations.... or request any info.
At Teleiose Contracting Limited, we are more willing to help you handle any of your building project; we can design, build and supervise your project. We can also help you calculate your BOQ.
