A 1 in 100 year storm could be a typhoon, a cyclone, a hurricane, or a tornado.
These storms have very strong winds, so what happens if the rain angle is actually horizontal?
If the rain was horizontal it wouldn’t hit the ground would it? So does the rain just keep going until it eventually evaporates?
But that can’t be right because we have floods.
And if these events are really once in 100 year storms, how come we can have one every year?
(refer to the comments below for the real answer). However continuing on for the rest of us….
The only logical answer is that the rain must come down somewhere, so once in every 100 years the rain comes down on your building.
At an angle of 63.4 degrees (2:1). Because that’s whats written in the Plumbing Code.
So it sort of takes it in turns, every 100 years your building is the lucky one, the structure at the end of the rainbow.
But not to worry, because if we use the plumbing code, we design all box gutters for this event.
We design for a 1 in 100 year storm with the rain coming down at an angle of 63.4 degrees (2:1)