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Parent Category: Code Tech Database
Category: Drainage

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Question: 08-22 Code Section: 7 Date: 7 May 2008 OBC 2006 Reference: 7.4.9.4.; 7.4.7.2

Question: (There is) a concern over what is a building drain and how should it be installed.

Interpretation: A sanitary building drain means a building drain that conducts sewage to a building sewer from the most upstream soil or waste stack, branch or fixture drain serving a water closet. The building drain is the lowest horizontal piping, including any vertical offset, that conducts sewage, clear water waste or storm water by gravity to a building sewer. 7.5.7.2(2) and (3) states that a sanitary building drain (minimum of 4 inch) is terminated at a 3 inch soil stack or a 3 inch waste stack or a 3 inch vent stack. 7.4.6.6 states that where a building drain enters the building above floor level, the building drain may be deemed to terminate at the first horizontal to vertical change of direction. A building drain must terminate at its most upstream end to the farthest SOIL STACK serving a water closet. This soil stack must extend a minimum of 3" to open air. If the stack is at the front of the building and a kitchen sink is at the back of the building then the building drain ends at the soil stack at the front of the building.

Approved at AMES 2008