More modern tiling and felt shingle systems can achieve lower slopes down to about 20 degrees.
Sloped lean to shed roof pitch.
A 4 12 pitch is around 18 5 degrees but not exactly.
You can also divide the rise over run multiply by 100 and get a percentage.
Lean to shed roofs develop an interesting problem as they get larger.
In other words if there is a 1 1 2 ridge board nailed into the wall and the width of the lean to is 96 then the run will be 94 1 2 96 1 1 2 94 1 2.
Thus a 4 12 pitch would be a 33 slope.
For lots more information on which roof finish to use for which slope and indicative costs.
Once installed your lean to style shed can look like an extension of your home.
For slopes below 20 degrees systems such as epdm fibreglass metal roofing can be used.
A ratio is the most common way of expressing roof pitch or roof slope but degrees are also possible.
If the roof pitch is very steep at all then it will rise to a height that becomes unsightly.
The run for a lean to shed rafter ending into a wall should account for the ridge board nailed into the wall where the tops of the rafters rest into.
A relatively steep pitch in excess of 40 degrees to be waterproof.
Some builders even choose to match it directly especially if the shed s roof is attached to the house on the high side and just one simple span pitch.
This ugly design is most often avoided by installing a low slope roof to keep the rise of the roof at a minimum.
Another widely used method is to follow the house s roof pitch on one side building the ridge off center then sloping down more drastically on the shorter side which will be closer to the house.
Some may say it is ugly.