For my tiny house i chose approximately 8 12 for the main roof and 4 12 for the shed dormer.
Minimum roof pitch for loft.
You can also divide the rise over run multiply by 100 and get a percentage.
The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7.
This image shows a relatively shallow roof pitch of 15 degrees.
A 4 12 pitch is around 18 5 degrees but not exactly.
The minimum slope of a roof depends on the roof s profile.
Pitched roofs can also be used to incorporate roof lights angled in a specific direction or dormer windows.
Where a property already has a steep pitched roof the eventual loft conversion will be much easier and ideally you are looking for headroom in the loft of around 2 2 to 2 6 meters.
The loft space would be much larger with a roof pitch of 45 degrees.
You could also opt for a pvc flat roofing membrane.
A pvc roof is a lot more durable and longer lasting that a conventional epdm rubber roofing system.
You need to consider the slope requirements of each panel to determine this minimum slope.
The first thing you want to do if you are trying to maximize the loft space in your design is decide on what the minimum roof slope that works for your climate and aesthetics.
However rise over run is more efficient and easier to understand for the average diyer.
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.
Minimum roof pitch for shingles.
Express the slope of a metal roof by a ratio which indicates the pitch of the roof.
The profile is the shape taken by the sheets when you bend them to form panels.
Thus a 4 12 pitch would be a 33 slope.
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.
This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.