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Shed roof pitch for snow.
In summary traditionally a roof pitch was determined by the climate and the available materials to achieve a dry building.
Pulling it all together.
You can use either 2 6 or 2 4 rafters for roofs with a 3 12 pitch or greater but it depends on the overall size of your shed.
For roofs that will experience heavy snow or wind and will span the same distance use 2 6 rafters.
The safest way to determine the pitch of an existing roof is to measure from inside your attic using a level tape measure and pencil.
If you are building a new roof however consider the climate to determine the correct pitch and proper materials.
Have a look at the shed roof design and shed roof construction pages to see the construction stages for shed roofs of other pitches and types.
The higher the roof pitch the more often the snow slides off.
Constructing a new shed roof at the desired pitch is as easy as knowing how to use a speed square.
People have been killed by snow avalanches sliding off roofs during big snow winters.
There are advantages and disadvantages to having a steep pitch versus a shallow or low pitch the most obvious of which is the roof s ability to shed or withstand heavy snow rain or wind.
Remember that pitch is calculated as the height or rise of a roof pitch over 12 inches of horizontal run.
This will extend the life of your roof.
The flip side to this is that it also becomes more expensive to build both in.
For roofs that won t experience heavy snow loads a gable roof can span up to 22 with 2 4 rafters.