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Question: 13-19 Code Section: 7 Date: 5 September 2013

OBC 2006 Reference:

Question Submitted: Hoping for some input on an install regarding RWL’S. The piping comes down thru the building and exits about 2 ft. above grade onto the ground where it is to flow to a C.B. about 20 ft away. The C.B. terminates at an approved retention pond. The pipe exiting is 8” in size. 
7.1.5.2.(2) says storm must connect to designated disposal location. Do you think this is a proper install? Could freezing be an issue? Your input would be greatly appreciated

Interpretation: The piping that is located in the building carrying the discharge from the roof drains are by definition, Leaders. They are installed for the purpose of directing rain water (commonly known as RWL’s) to a storm building drain, storm building sewer or other approved place of disposal (by the authority having jurisdiction), such as a storm retention pond.

Rainwater leaders are considered plumbing and must be sized accordingly. A RWL discharging out the wall to the surface may be deemed a designated storm water disposal location if it is designed to be part of the storm management plan with positive drainage away from the building (in this case, a catch basin to a retention pond).

While this type of installation is not a normal practice for larger, non-residential type buildings (as there is usually an assembly of pipes and fittings connecting to a Storm Building Sewer)the OBC does not prohibit this, provided a hazardous condition is not created, nor is the building damaged, as required by Articles 5.6.2.2 and 5.7.1.1., Div. B, OBC.

5.6.2.2. Accumulation and Disposal
(1) Where water, snow or ice can accumulate on a building, provision shall be made to minimize the likelihood of hazardous conditions arising from such accumulation.

5.7.1.1. Prevention of Accumulation and Ingress
(1) Except as provided in Sentence (3), the building shall be located, the building site graded or catch basins installed so that surface water will not accumulate against the building.

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