Having decided on the material, select the angle of inclination of the roof. In addition to the material, the main limiting factor will be the amount of snow that drops in winter. The more precipitation, the cooler the roof should be. If you decide to cover the roof with corrugated board, then the angle may be minimal – the iron does not delay snow. In the low -snow areas there is enough inclination of 10 degrees, where there is more precipitation – up to thirty degrees.
The slate denses snow, therefore, depending on the region, the minimum corner of the roof can vary from 45 to 60 degrees.
A fairly common mistake of novice builders is to make a larger roof angle in order to leave more space under it. If you want to make another room under the roof, it is better to make a gable roof using the following technology. You build a smaller room above the first floor – the height and width you need. The length of this room is equal to the length of the first floor, the width is slightly smaller than the width of the first floor. From the upper edge of the second floor, lower the rafters to the upper edge of the first floor. It turns out part of the roof with a large angle of inclination. If the rafters are continued over the second floor at the same angle, then the roof will be unreasonably high and costly in material. Therefore, it is easier to make a roof with a minimum angle of inclination above the second floor. (Maybe add a picture to the text? If necessary, I can make such a drawing in the core).