How many sheets are needed to cover a roof?

To calculate the number of sheets needed to cover a roof, the useful surface per sheet must be considered, itself depending on the overlapping rules applying according to the roof structure. Some local specificity in the installation guidelines may apply. Please consult local installation guide. For a precize calculation of the roofing material, each detail of the roof must be considered.
Onduline Classic (10 corrugations) has a gross surface of 1,90sqm. Following installation guidelines:
- For the lowest roof pitches (9% to 17%) (5° to 10°), considering an end overlap of 30 cm and a side overlap of 2 corrugations, Onduline Classic useful surface of 1,29 sqm. 
- From standard roof pitches (17% to 27%) (10° to 15°), considering an end overlap of 20cm and a side overlap of 1 corrugation, Onduline Classic useful surface is 1,54 sqm. 
- For highest pitched roofs (over 27%) (>15°) , considering an end overlap of 17cm and a side overlap of 1 corrugation, Onduline Classic useful surface is 1,56 sqm . 
Onduvilla tile has a gross surface of 0,42 sqm and a useful surface of 0,31sqm. 
You may get in touch with a professional or with Onduline local technical team for a more accurate answer for your project.