Is it OK to expose drain pipes on the exterior of your house

draindrainage

I live in San Francisco, and my kitchen sink drain goes through my wall towards outside of the wall of the house into a light well. The steel pipes have rusted out so I want to replace them with ABS. Does any one know if this is legal or to code in SF? I have read that it is recommended to use a heavier duty pipe for more resistance to UV rays so maybe that would be “more” to code. Please advise!

Best Answer

I spoken with the San Francisco Building Code inspector and they said ABS exposed pipes are allowed as long as it is coated with UV protected paint since it’s located outdoors. Also ABS used for DWV applications are only allowed for buildings up to 2-stories private and commercial. For mixed material couplers, I would need to find a coupler made specifically for steel to plastic. Thanks @jim for telling me just to call the inspector.