How to calculate a gable roof?

How to calculate a gable roof? Namely: the number of crates, the load on the roof, as well as a number of the necessary material for the construction of this type of roof. Going to cover with a metal tile.
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To calculate a gable roof with different angles on each side, you need to make two calculations shed roof with the necessary parameters. The easiest way to do this using 3D calculator online https://kalk.pro/roofs/ Enter the parameters and get an estimate)
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