Rain fall below a area under canopy /roof with sides open 1

[jai009]

Hi All,
is there any guideline or code which indicates the amount of rain which can fall in an area provided with roof. i.e. some guideline which relates the roof pitch with the sheltered area.
your response are appreciated.
thanks

 

[phamENG]

I'm going to go with no? An open space is an open space. Water can come in. All surfaces should be treated as exterior (except, perhaps, roof framing that is generally protected by the roof itself or some other waterproof surface).

 

[JLNJ]

All I can think of is that I believe there are some provisions in the mechanical code about rainfall hitting vertical surface. It has to do with sizing roof drains next to a high bay wall, but you might be able to extrapolate that to rain which would find its way "under" your roof and onto the surface below.

 

[Lomarandil]

Sometimes the architects have data on it regarding exterior cladding performance.

But it's all a matter of statistics... there is no real "sheltered" area, just decreasing probability of rainfall corresponding to the winds high enough to drive that rain under the overhang. Which varies by climate/region.

 

[dik]

I suspect that even enhanced condensation issues can be a problem.

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-Dik

 

[jai009]

Hi,
thanks for all your responses.
so there is no emperical formulae or relation between the rain hitting the ground under the roof and the angle of the roof. It is a matter of statistic.
thanks

 

[HTURKAK]

My approach would be similar to the snow loads ..

I would consider the local rainfall intensity at flat roof will be applied over a portion of that flooring level near any open edge with 45 degr. and take necessary measurements ..

Excerp from ASCE SNOW LOADS .

My opinion...





I cannot give you the formula for success, but I can give you the formula for failure..It is: Try to please everybody.

 

[IRstuff]

some guideline which relates the roof pitch with the sheltered area.

You should already be able to guess that roof pitch has zero to do with protecting from rain from how much or how little an umbrella protects you from rain. The only factors that really matter are how far away you are from the perimeter of the roof, how high or low the roof is, and how much wind accompanies the rain. I have a vivid memory of taking my kids to the Cleveland Science Museum and seeing some lake effects snow basically going sideways from the wind. Nevertheless, you can surely imagine that if you were under a 1-story roof with 1-mile linear dimensions that very little rain might reach the center, although in a hurricane or tornado, even that might not be enough.

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[jai009]

thanks all for your valuable comments.