How to Estimate Corrugated Metal Roofing Sheets
In this article, you are going to learn how to estimate the quantity of roofing sheets required to roof your house
ESTIMATION
How to Estimate Corrugated Metal Roofing Sheets
Table of contents
Introduction
Understanding Roofing Area and Effective Area
How to Calculate Roofing Area
How to Find the Effective Area of a Roofing Sheet
How to Calculate the Number of Sheets Needed
Example 1: Shade Roof Calculation
Example 2: Hipped Roof Calculation
Conclusion
FAQs
Core concept or idea
In this article, you are going to learn how to estimate the quantity of roofing sheets required to roof your house
Understanding Roofing Area and Effective Area
Before diving into calculations, lets first clearly understand the meaning of roofing area and effective area.
The roofing area refers to the total surface area of the roof whereas effective area refers to the usable portion of a single roofing sheet that remains after deducting the area for overlaps.
Calculating the Roofing Area
To determine the roofing area, you need to measure the length and width of the roof or you can simply measure the top view length and width of your house
For example, consider a shade roof with the following dimensions:
Length: 10 meters
Width: 5 meters
Overhang: 0.3 meters on each side
Pitch Angle: 30 degrees
To calculate the total roofing length, add the building length to the overhang on both sides:
Total Roofing Length = Building Length + Overhang (both sides)
Total Roofing Length = 10 m + 0.3 m + 0.3 m = 10.6 m
Next, calculate the roofing width using trigonometry:
Roofing Width = Hypotenuse of the Triangle
Using the 30-degree pitch angle, we apply the Pythagorean theorem:
Roofing Width = 5 m / cos(30°) = 5.77m
Now, add the overhang to the roofing width:
Total Roofing Width = 5.77 m + 0.3 m + 0.3 m = 6.37 m
With the total roofing dimensions calculated, the roofing area can be determined:
Roofing Area = Total Roofing Length x Total Roofing Width
Roofing Area = 10.6 m x 6.37 m = 67.5 m²
Determining the Effective Area of a Roofing Sheet
Next, we need to find out the effective area of a single roofing sheet. Assuming the dimensions of the sheet are as follows:
Length: 3 meters
Width: 0.9 meters
Consider the overlaps:
Width Overlap: 0.075 m (75 mm)
Length Overlap: 0.25 m (250 mm) in most cases we don’t need this length overlap since we order exact length roofing sheets which do not need cutting or overlapping at the longer side
To find the effective width:
Effective Width = Total Width - Width Overlap
Effective Width = 0.9 m - 0.075 m = 0.825 m
For the effective length:
Effective Length = Total Length - Length Overlap
Effective Length = 3 m - 0.25 m = 2.75 m
The effective area of a single sheet is calculated as:
Effective Area = Effective Length x Effective Width
Effective Area = 2.75 m x 0.825 m = 2.27 m²
Calculating the Number of Roofing Sheets Required
Now that we have both the roofing area and the effective area meaning we can calculate the number of roofing sheets needed with ease
Number of Sheets = Roofing Area / Effective Area
Number of Sheets = 67.5 m² / 2.27 m² = 29.7 sheets
Rounding up, you will need approximately 30 sheets for this shade roof.
Example 2: Estimating a Hipped Roof
Now, let’s consider a hipped roof. Assume the following dimensions:
Main Building Length: 24 meters
Main Building Width: 6 meters
Extension Length: 4 meters
Extension Width: 2 meters
First, calculate the area for both sections:
Main Building Area = Length x Width
Main Building Area = 24 m x 6 m = 144 m²
Extension Area = Length x Width
Extension Area = 4 m x 2 m = 8 m²
Adding these areas gives:
Total Area = Main Building Area + Extension Area = 144 m² + 8 m² = 152 m²
Assuming a 30% safety margin to account for pitch, the total roof area is:
Total Roof Area = Total Area x 1.3
Total Roof Area = 152 m² x 1.3 = 197.6 m²
Effective Area for the Hipped Roof
Using the same effective dimensions for a roofing sheet as before:
Effective Area = Effective Length x Effective Width
Effective Area = 2.75 m x 0.825 m = 2.27 m²
Final Calculation of Roofing Sheets for Hipped Roof
Finally, calculate the number of sheets required:
Number of Sheets = Total Roof Area / Effective Area
Number of Sheets = 197.6 m² / 2.27 m² = 87.05 sheets
After Rounding up, you will need approximately 88 sheets for this hipped roof.
Conclusion
In summary, estimating the number of corrugated metal roofing sheets, you simply get the roofing area and dividing it by the effective area of a single sheet
you then determine the quantity needed for your project.
This method ensures you have an accurate estimate, reducing waste and saving costs.