How to calculate numbers of roofing sheets from a pitch roof

The most common roof style is the pitch roof and the building is usually

divided at the center which is the apex.
The pitch roof is the easiest to calculate though I won’t bore you with

details, but you can ask your contractor for the size of each roofing

sheet except you are using longspan aluminium roofing sheet which can be cut to exact lenght of the roof.
To make fast calculation, measure the length of the side of building let

say ‘x’, measure the breadth ‘y’. To get an approximate surface area we

will add an arbitrary value for the difference in length due to the pitch

or depth of roof.
So lets say for a house of total length of the front is 1.8m or 60ft

and side which is the longer part is 27m or 90ft.
Area =length of front of house x side of house=18 x 27=486m2
Add allowance for the pitch or depth 20% of Area=20% + 486m =583.2m2
Now find out the length and breadth of each roofing sheet and also

multiply length by breadth.
Assuming the ceilling sheet is 3.6m in length and 1.8m in breadth
Then area of roofing sheet =3.6 x 1.8 =6.48m2
Therefore total numbers of roofing sheets needed approximately is
(Area of building + Allowance)/area of one roofing sheet =583.2/6.48m
=90 sheets
Please note that this is not a standard way of approximating but this is

derived based on my experience for your enjoyment. In any case there is

never a standard way.

An architect with decades of experience


  1. u are doing a great joy. im quite naive about building construction. i`ve learnt few things now.
    please can you assist to calcul;ate an estimate for building a simple story building with three bed room , two tolits,chitchen
    simple sitting/dinning room..
    how much will decking of such cost?
    what is the cost of drawing plan of this simple building.
    any other advice will be highly appreciated

    1. Thanks for the question but to calculate all these requires you have a plan and location if not you will not really get the right estimate. I will send you a mail now.

  2. pls can u assist me in caculating the total number alluminium roofing sheet to be used for 2 3bed room hse at meiran alimosho local govt area. and all the necessary things to be used in finishing the roofing sheet. and which best sheet to be bought e.g .55mm or .45mm i just guess as i dont know how they are measured. thanks dipo

    1. Dipo,
      The aluminium company will do that for you easily and the best presently is Tower. .55mm is the right guage to use.

  3. I really commend ur wonderful effort in dis forum. Bt pls i need u 2 send 2 my mail d roofing material 2 go 4 (almn or zinc) wit considerations on prices difference. Pls. Thnx n God bless.

  4. Well done on this forumn, read through some of your post and they have been helpful and practical indeed.
    I am doing my masters in Architecture and would like it if you send recommendations of people who would want a design-floor plans, elevation, etc; both 2D AND 3D.
    Please reply to my email( for information on the possibility of this.

  5. Hi, dis forum is vry practical in nature.
    Pls, i wuld luv to knw 4rm u, how to compute d number of woods truss and der sizes from a building plan. Tanks alot, takia!

  6. hi there im a 21 year old mail who just started working at Cash Build 2months ago and im eager to obtain the position of sales co-ordinator (doing building plans for clients) but i’ve got the basics but am struggling to calculate roof trusses and tiles per square meter ect. Any suggestions?

  7. Emma, thank yu for the great work ure doing for people.Advise me on the type of roofing sheets within the minimum amount I have.My building is at the roofing stage now in Oyo State.I cant afford Alluminium.I want to go for local corrugated iron sheets. I learnt they are of diff. types.I saw one in Rivers state #14000 per bundle (20sheets).I still want the best within the above amount.I told my supplier that the brand is swarm and not hand.He said govt. has bond it.But he has diff. types and colours.How many sheets will I use for 4bedrm flat of 188.35m2 including the 20% extra. What type of local sheets do I go for within that above stated sum, what shld be the thickness, lenght etc.

  8. i quite appreciate what u are doing, i must say u have removed fear from my mind when i think of building a structure of my own.

  9. My building is at the roofing stage now in Lagos State.I want to use Alluminium sheet. I have searched for diff types but not yet convinced. Someone by my side just finished his roofing and he said he bought his own at #14600/bundle (15 sheets). How many sheets will I use for 4bedrm flat of 209.952m2 including the 20% extra. What type of local sheets do I go for within that above stated sum, what shld be the thickness, lenght.

  10. Men! U are doing a 9ce job. May d lord rewards U accordingly. Please what is different btw imported and locally manufactured aluminium roofing sheet and which of d two is good for our climate.
    Also, what are the prices ranges of different type of Aluminium roofing sheet. Is nigerite roofing sheet better than aluminium roofing sheet?

  11. am samson am into aluminium roofin and window, pls if u need a supplyer, installer and fabrication of ur house pls contact me on 08034496743,i will give d best and a cheaper rate. THANKS

  12. What a great assistance you are rendering,can you give me the cost of various thickness of long span roofing sheet,cost per square meter and the maximum sq meter that can roof a two flat of three bedroom each and the dimension of the building is 87×38 feet.

    Also link me to someone that will do a good job for me.

  13. Dear editor, what u are giving out her can neva be paid for even in an institution of learning cos lecturers mentality dis days are usually of the fear of not wanting the students to compete with dem…… May God bless and continue to refill ur knowlegde and bless the works of thy hand, for exposing us all to the nitty-gritties of building construction. Xo-Xo….

    1. Building materials? I think you can get those from the market. But for an estimate you’ll need to present plan before that can be done effectively.

  14. Guy u re doin a great job whch i realy apriciate bt re u QS if yes u need to do it profesionaly cos there re some layman error in ur calculation

  15. Pls i can u help me out.i realy dont know how to calculate d number of woods to b used in construction.i am a graduate of architecture.pls i reside in ilorin.i wil apreciate if u can refer pple to me.07039104920

  16. Pls can u help me out.i realy dont know how to calculate d number of woods to b used in construction.i am a graduate of architecture.pls i reside in ilorin.i wil apreciate if u can refer pple to me.07039104920

  17. Please l need to know exact price for standard aluminium roofing sheet, either per 1 or bundle and how many pieces in a bundle. pls urgently needed

  18. hello, do you sell/suppy roofing sheets? If yes could you tell me the various types and prices? I am building in magboro area and I am ready to begin roofing. I am trying to get 2 quotes to compare and then chose the most qualitative that I can afford. I will forward my plan when I get a response. thank you so much.

  19. Emma, thank you for the great work you are doing. for people. Please can you advise me on the right aluminum roofing sheet to use for my building. My building is at roofing stage now but I am confused on the type of roofing to use. Please, help me list different types of aluminum roofing sheets, sizes/ thickness/measurements and their prices. I really want the best. The house is a storey building duplex house.

  20. smiles ” Emma great work will only need idea. but i strongly disagree with ur pitch roof calculation i believe u need to apply a pythagoras theorem formular, and also consider the projection of 600mm including ur waste allowable.

  21. Thank for ur help in roof calculation for carcassing u could also include scarf joint I.e. The overlapping of d different members since each length is assumed 3,6m when dealing with length more than that there is need for overlapping

  22. Thank you, please keep up the good work, can you please help me to calculate the number of zinc i will use to roof a pen of 22ft by 80ft. Thank you

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