The roof drain is somewhere in the middle of the roof area, and the roof slopes upward from that point to 4.5 inches at the parapet where the scupper is located.
If this is correct, then the entire roof would be under water before the scuppers would even begin to drain, which doesn't seem like a sound solution.
I know California uses the UPC, so I'm not sure exactly what it states, but the IPC indicates that emergency drains or scuppers shall be sized to prevent the depth of water from exceeding that for which the roof was designed. Therefore, you would need to design the roof to support all that water load.
I suggest just putting in the second drain next to the main roof drain.
With that said, the code does allow for other things as long as the structural capacity of the roof is adequate. Heck, if you are doing an IRMA roof, or a green roof allowing standing water up there could be part of the design.
Thank you both kindly for your insight!
The roof is designed with a garden assembly but I'll be sure to incorporate an overflow at 2" above the low point.
Good to do both.
quote:Originally posted by rlga_AZ:
Overflow drains are also required to be piped separately and they cannot be tied into a storm drain system--they must open to daylight so that if water is coming out of the overflow drain, you know there is a problem.
Yup. So you can walk into a store where the overflow is pouring down directly in front of the main entrance and realize that the occupants /employees inside are ignoring it completely. Ask me how I know this; and about the surprised attitude when I mentioned it to the manager... LOL
see this all the time...
or over a window, or onto a patio, etc. etc.,
same thing with condensate overflows, along with trail of algae-slick run-off from slow flow...
and when you point out something like this, occupants just say they thought it was a leaking pipe, but never wonder why...
quote:occupants just say they thought it was a leaking pipe...
well, IT IS...