How to calculate numbers of blocks from a building plan.
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Most asked question from a would be house owner is always how many blocks do I need to get my building completed. Hence this topic is written with illustrations to make it easy for you to do
the calculations yourself from the plan your architect gave you.
The plan above is for a 2 bedroom bungallow, so we are going to start from the basics having in
mind these factors-
i)The lenght of a block is 0.45m or 450mm or 18″
ii)The width of thickness varies -150mm or 6″ and 225mm or 9″ which are most common.
ii)Taking for a general or average purpose, the blocks laid from foundation to dpc(german or
oversite concrete) is 4 coaches/levels. From dpc to the base of window another 4 coaches,from
base of window to top of window another 5 coaches, then from top of window to base of roof
another 3 coaches, neglecting the lintel or concrete on top of window.
Now with these parameters let calculate the plan above which has a wall of 150mm or 6″ all
through.
Add the length and breadth of the blockwall for external and internal
Therefore (A)9,400mm +9,600mm(B)+9400(C)+9600(D)=38,000mm or 38m
Now add the internal walls too
(Follow the grid lines and check the corresponding dimensions on plan remember 150mm is the
block width)
(Grid 7)150+3600+150+150+3600+150=7,800mm or 7.8m
(Grid 6)1350+150+2250+150+825+675+150=5,550mm or 5.55m
(Grid 1b)800+2400+1300+900+100=5,500mm or 5.5m
(Grid 2)2600+900+100+150+100+900+500+150=5,400mm or 5.4m
(Grid 3)1800+150+650+900+250+900+1450=6,100mm or 6.1m
(Grid 3b-Kitchen)900+50+1200+50+150=2,350 or 2.35m
(Grid 7b toilet)1800 or 1.8m
Total internal walls=34,500mm or 34.5m
Therefore Total walls=38,000mm +34,500mm=72,500mm or 72.5m
Now for the first 4 coaches to dpc level the wall will run right through, i.e the spaces for
doors or windows are not left out (n/b- blocks are used in relatively strong and stable soil not
waterlogged area that requires concrete instead).
Divide the sum by 450mm to know the numbers needed for one level/layer/coach of blocks
72,500/450=161 blocks
From dpc level to roof lets take the numbers of coaches to be 4+5+3=12 coaches
then multiply the numbers of blocks for each coach above by 12
161 x 12=1932 blocks
Don’t forget we have windows and doors spaces which we need to remove,for each window of 1200mm
take numbers of the block to be 14 (i.e 1200/230=5.2 and 1200/450=2.6 ,5.3 x2.6=14 approx
Now count the numbers of 1200mm windows and multiply by 14
Total numbers of 1200mm windows as counted on plan is 12 (note 2400mm window was taken as two of
1200mm window)
i.e 11 x 14 =154 blocks + 7 blocks for 600mm window for toilet. Total=161 blocks
Now calculate for doors,Numbers of blocks for a door of 900mm is 18.
height of a door(2100/225=9)+width of a door (900mm/450mm=2). so 9 x2 =18 blocks for each door.
Multiply 18 by numbers of doors=18 x8=144 blocks
Add 144+161=305 blocks,then remove from total blocks of 644 (for dpc) + 1932
Total numbers of blocks reqd=2,271 blocks
For a quick calculation, having the entire length to be 72,500mm. Take for a bungallow total
lenght from foundation to roof to be 1,200mm +3000mm=4200mm
Then calculate the surface area which is 72,500 x 4200 and convert to meters
72.5m x 4.2m=304.5m2
Remove surface areas of windows and doors
For window, height is 1.2m and total is 11
i.e 1.2m x 1.2m x 11=15.84m2 +0.6 x0.6(toilet window)=16.2m2
For doors, height is 2.1m while width is 0.9m
i.e 0.9 x 2.1 x 8(nos of doors)=15.12
Total area for doors and windows=16.2m2 +15.12m2=31.32m2
Remove 31.32m2 from 304.5m2=273.18m2
Now divide this by surface area of a block which is 0.225 x 0.45=0.10125
The blocks reqd caculated by this method is 273.18m2/0.10125=2,698 blocks
Note a difference of about 400 blocks from the two calculations. Of course you can’t get exactly
the numbers you need but the first method is close to it. And calculations are not 100% true
because of these factors
1-The mortar space was not considered
2-Blocks that will be wasted due to breakages e.t.c
Tags: 2 bedroom bungalow, blocks, bricks, calculate numbers of blocks, dpc, estimate
October 24th, 2010 at 3:21 pm
man you a doing a wonderfull job but dont take out of the table for we engineers, but you a good keep it up
October 30th, 2010 at 6:07 pm
a chartered QS will calculate the same way. thank you for a job well done
December 30th, 2010 at 7:49 pm
Your works has being providing great information that are accurate. Thanks and God bless
January 17th, 2011 at 10:16 am
I really like this. Thanks a lot.
January 17th, 2011 at 10:07 pm
Thank you.
January 19th, 2011 at 7:45 pm
what an emperical formaula. thank u
March 10th, 2011 at 9:36 am
How many 6inches block and 9inches block can i use to raise two flats each with 3 bedroom from german floor level?
May 11th, 2011 at 8:03 pm
thank u for revealing this method of calculations, now i know what to plan and budget for my building.
July 4th, 2011 at 4:05 pm
can u train a layman briclayer
July 5th, 2011 at 12:56 am
No I can’t but I have bricklayers such person can learn from.
Thanks
July 8th, 2011 at 12:42 pm
you dnt want the contractors to earn 4m thetr fruit.
July 18th, 2011 at 9:47 am
Thanks, I have applied it and worked 97%.
July 19th, 2011 at 12:47 pm
Is great having people like you in this our part of the world.
Keep the flag flying.
Thank you.
July 19th, 2011 at 5:51 pm
This is simply brilliant! I am amazed! Thank you
July 19th, 2011 at 10:10 pm
Thanks
July 19th, 2011 at 10:15 pm
This site is not to disenfranchise builders but is to encourage more Nigerians and Africa in general to build their own houses.
Thanks
July 27th, 2011 at 7:54 am
Knowledge is power and information a weapon when in the hands of the wise. Having the quality of information you are supplying on your site will definitely keep us ahead of fraudulent building contractors. But I dare to say that supervision can also go a long way in ensuring getting the right kind and quality of building services we require.
August 8th, 2011 at 6:29 pm
I prefer method 1 plus 10% to make up for differences and breakages. This would give us 2271*227=2498. Lets say 2500 blocks which is fair and much more realistic than method 2. I’ll write an excel prog to do this calculations for me for every plan. I will find a way to share when I do.
September 19th, 2011 at 2:13 pm
Man, you are doing a wonderful job. I wonder if there is any nigerian that can do this without asking for money. God will continue to bless you.
Please tell me, how many blocks can I use to put up a 4-bedroom flat.
Regds.
Martins
October 12th, 2011 at 8:27 am
Man, dis is a free Engineering course online, u ar gud, keep d gud wk up
November 3rd, 2011 at 10:28 pm
I’m short of words, don’t know what to say to you, God Bless you for posting this but pls don’t remove anything from here as we engineers will always need it.
December 17th, 2011 at 12:03 am
Thank you for your practical knowledge inculcate in me.
December 29th, 2011 at 5:03 pm
This is very good!u have real orientation about building.thanks, u ar a blessing
January 9th, 2012 at 5:03 am
I really enjoyed this online,thanks you ve really help me.