Roof Pitch For Water Runoff

The ratio between width and height is much smaller with a low pitch roof.

Roof pitch for water runoff.

How water sheds off a roof depends on how much rain falls in that location and how quickly it needs to drain. Roof pitch refers to the slope which the rafter creates. When installing a metal roof that has considerable formed thickness to is such as a shake or tile profile using 6 gutters would work better than 5 again to keep water from overshooting them. If it is a large roof it is recommended to have drains placed at multiple locations within the area of the roof.

You can assess this in two ways either as the roof pitch angles which the rafters make with the horizontal or the proportion between the run and the rise of the roof. A wide roof with a steep slope will lead to faster runoff hence necessitating a slightly steeper slope for effective discharge of the rain water. High pitch roof pros. Since the pitch of the roof is lower it can act as a catch all for tree limbs and other debris.

A 4 12 slope is enough to accommodate water runoff but is not suitable for regions that are affected by heavy snowfall. My own house with a metal roof of course is a 12 12 pitch and everything is just fine. Therefore attic space can be at a premium with a low pitch roof. Every roof needs drainage.

This forms an angle of 18 5 between the horizontal section and the roof and creates a gentle incline that is seen as a midpoint between a low pitch and medium pitch roof. Care must be given so that debris does not collect and thus cause damage. To put it in perspective the angle of this slope would be around 30 degrees. A small roof with a shorter length on the other hand will not collect a lot of water within a short period of time and will work just fine with the minimum roof slope for drainage.

While a 4 12 pitch roof has enough slope for water runoff it s often too low for regions with heavy snowfall which can put considerable weight on the roof s structure. Often you express roof pitch as the ratio between the rise and the run in the form of x 12. This means that the rise of the slope goes up or down 8 inches for every 12 inches. I do suggest hanging gutters as high as possible so that water does not over shoot them.