The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.
New york construction roof pitch minimum yates county.
Asphalt shingles continue to be the most widely installed roof covering option in north america.
So you would need to pick the right option as most regular standing seam metal roofs will require a roof pitch of 2 12 or even 3 12 at a minimum.
You can enter this value either as a ratio x 12 or as an angle whichever suits you better.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
For low pitch roofs building codes may require larger dimension rafters.
You could also opt for a pvc flat roofing membrane.
With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 20 0 for slate roofs.
For instance if your roof has a steep pitch you may be able to use 2 inch by 4 inch rafters but if your roof has a low pitch building code may require that you used 2 inch by 6 inch or 2 inch by 8.
The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.
But since there is still a wide variety of slate roofing systems there are occasions when the minimum pitch can go down to as low as 15 0 depending on the uniqueness of the roof.
As roof pitch is lowered the weight burden on the rafters increases.
They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends.
A penthouse or other projection above the roof in structures of other than type i construction shall not exceed 28 feet 8534 mm above the roof where used as an enclosure for tanks or for elevators that run to the roof and in all other cases shall not extend more than 18 feet 5486 mm above the roof.
Intuitively this is the number of inches of snow on your roof in the place where the cover is the thickest.
A pvc roof is a lot more durable and longer lasting that a conventional epdm rubber roofing system.