Building Drain - Stack Connection

[Stephan82]

Hello

Thank you in advance for your assistance.

My question pertains to the horizontal building drain layout. I'm doing a renovation to my house. I'm moving and adding bathrooms so I have to change the building drain. Is there a minimum distance that 45 WYE in the building drain that branch out to connect the vertical stacks have to be spaced apart?

I have attached my plan for the building drain layout

 

[Stephan82]

In reading up on the installation procedure for a Backwater Valve (seriously considering one given all the flooding in Ontario at the moment and the ease of install given my current rebuilt), I believe I may have stumbled upon a standard distance. In the instructions it states that in order to achieve laminar flow through the valve body that no 45 WYE should be within 2 feet. I will go with this unless I find something else in the OBC.