Minimum Roof Angle For Rain

The only logical answer is that the rain must come down somewhere so once in every 100 years the rain comes down onyour building.

Minimum roof angle for rain.

I reckon that rain is about 45 degrees. This is the basis for calculating the angle which is approximately a 1 19 degree slope. This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end. Going with a 6 12 roof slope instead of 7 12 will work slightly better in terms of minimizing the overall wind uplift pressures while also adequately mitigating for any wind driven rain issues and retaining the profile of a true single story structure from the wind uplift mitigation perspective.

If the run requires two sections of gutter overlap them by 8 inches and use a 3 8 inch long self tapping stainless steel screws or pop rivets in two rows of four each to join them. 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. Because that s whats written in the plumbing code. Pitch is a measure of the steepness of a roof.

Flat roof slope minimum according to the international building code the typical built up flat roof that uses tar or asphalt goes by the guideline that for every foot 12 inches of a flat roof a minimum of inch must step up or down. As a general rule gutter slope is set at 1 4 inch per 10 feet of guttering. At an angle of 63 4 degrees 2 1. According to this code the minimum slope for asphalt shingles is 17 degrees or two vertical units to twelve units in the horizontal.

If the gutter continues around a corner cut the appropriate angle typically 45 degrees on that end. The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run. For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e. A flat roof would have a 2 12 pitch while the average roof pitch would be between 4 12 and 9 12.

A 4 12 is a roof slope that rises by 4 inches for every 12 inches across. A reputable roofing contractor will be familiar with the pitch required by these codes.