Roofing Materials: How to Calculate Roofing Sheets (Mabati) needed
Knowing how to estimate roofing materials is important. Not only will it help eliminate waste, but it will also ensure that you buy just enough for the project. Below we show you how to estimate roofing materials for your next project.
Find the area in square metres of the roof.
To get an approximate surface area, we will need to multiply the length and width of the house.
Area =length of front of house x width of house
So let’s say for a house of total length of the front is 11.4m and side which is the longer part is 4.6m and a side extension of 2.96 M by 3.8M
The calculations are captured below
As indicated, we add an arbitrary value as a safety factor for the difference in length due to the pitch or depth of roof or roof rise.
Add allowance for the pitch or depth or roof rise, say 30% of Area
The Area will be : (11.4 X 4.6)m2+ (3.8X 2.96)m2 X 1.3 (30%)=82.8m2.
How to calculate the number of Iron Sheets
Now find out the length and breadth of each roofing sheet and also multiply length by breadth. Assuming the ceiling sheet is 3 m in length and 1m in breadth,
Then area of roofing sheet =3 x 1 = 3m2
Therefore total numbers of roofing sheets needed approximately is
(Area of building + Allowance)/area of one roofing sheet
=82.8/3m = 28 Mabati Sheets
Please note that this is not a standard way of approximating but this is derived based on site experience. In any case there is no particular standard way.
With your estimate is also the Ridges, Valleys and Gutters.
Ridges and Valleys are the roof materials you use that will cover and seal up the points where two leaves of your aluminium sheets meet to protect the interior from rain, it usually overlaps the two adjacent leaves of roofing sheets .
A gutter is usually underneath, it gathers rainfall and help to channel it to wherever deem fits according to design. Is at the taper ends of two adjacent leaves of aluminium sheets to collect water.
The difference between gutter and ridge . While the ridge is up protecting rain water the gutter is down collecting rain water and channeling to some drains.