# Are over flow scuppers required for scuppers that are primary roof drains



## Inco (Aug 22, 2020)

Are over flow scuppers required with primary scuppers for roof drainage


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## ICE (Aug 22, 2020)

CBC
1502.2 Secondary (emergency overflow) drains or scuppers. Where roof drains are required, secondary (emergency overflow) roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason. The installation and sizing of secondary emergency overflow drains, leaders and conductors shall comply with Chapter 11 of the California Plumbing Code.

CRC                  
R903.4.1 Secondary (emergency overflow) drains or scuppers. Where roof drains are required, secondary emergency overflow roof drains or scuppers shall be provided where the roof perimeter construction extends above the roof in such a manner that water will be entrapped if the primary drains allow buildup for any reason. Overflow drains having the same size as the roof drains shall be installed with the inlet flow line located 2 inches above the low point of the roof, or overflow scuppers having three times the size of the roof drains and having a minimum opening height of 4 inches shall be installed in the adjacent parapet walls with the inlet flow located 2 inches above the low point of the roof served. The installation and sizing of overflow drains, leaders and con- ductors shall comply with Sections 1106 and 1108 of the California Plumbing Code, as applicable.


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## steveray (Aug 24, 2020)

So that is a yes.....Unless the roof will support the water until it gets over the parapet if the primary scuppers get clogged.


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## mtlogcabin (Aug 25, 2020)

Look around and you will find them installed everywhere


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## ICE (Aug 25, 2020)

steveray said:


> So that is a yes.....*Unless the roof will support the water *until it gets over the parapet if the primary scuppers get clogged.



Ya,,,,I don't think so.


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## steveray (Aug 25, 2020)

Me neither....But they could...

1101.7 Roof design. Roofs shall be designed for the maximum
possible depth of water that will pond thereon as determined
by the relative levels of roof deck and overflow weirs,
scuppers, edges or serviceable drains in combination with the
deflected structural elements. In determining the maximum
possible depth of water, all primary roof drainage means shall
be assumed to be blocked. The maximum possible depth of
water on the roof shall include the height of the water
required above the inlet of the secondary roof drainage means
to achieve the required flow rate of the secondary drainage
means to accommodate the design rainfall rate as required by
Section 1106.


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## mtlogcabin (Aug 25, 2020)

Ponding was pretty common way to help with cooling large industrial buildings in the last century.

"Roof cooling began over 60 years ago. Ponding, rather than evaporation, was the original concept. Although it had some drawbacks, the overall results were very satisfactory for this cooling concept. Ponding was good, but would not work on all roofs, and had too many negative effects on the roof. Engineers worked to change the concept of roof cooling from a ponding to an evaporative technique." 






						Plant Engineering | Consider evaporative roof cooling to reduce your HVAC load
					

Plant Engineering - HVAC Cooling the energy crisis, from the top To reduce the load on air conditioning systems, a growing number of companies are cooling the building from




					www.plantengineering.com


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## ICE (Aug 25, 2020)

steveray said:


> Me neither....But they could...
> 
> 1101.7 Roof design. Roofs shall be designed for the maximum
> possible depth of water that will pond thereon as determined
> ...





steveray said:


> Me neither....But they could...
> 
> 1101.7 Roof design. Roofs shall be designed for the maximum
> possible depth of water that will pond thereon as determined
> ...


What code book is this?  Is this not to take into consideration the amount of ponding before the secondary drain starts to work?


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## steveray (Aug 26, 2020)

ICE said:


> What code book is this?  Is this not to take into consideration the amount of ponding before the secondary drain starts to work?


Yes...But technically there is no actual limit to what that height could be other than the structural limits of the building....If the secondary drain is the roof edge....


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