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Sammy 2 02-23-2012 11:34 PM

What is better ?
 
I have a 3 inch main stack that goes down through my main floor into my crawlspace. Once there it goes 5 feet to the gravel floor, makes a 90 degree turn and continues on, sloped above ground, and eventually nosedives down and onward to the street drain. I want to tie in a new toilet, which is better ; ty into the vertical stack or the sloped horizontal pipe ?

oh'mike 02-24-2012 04:55 AM

Need more info---Both are acceptable---is a picture possible?

Sammy 2 02-24-2012 11:08 AM

I will be doing a drawing, coming soon :) .

Sammy 2 02-24-2012 10:49 PM

2 Attachment(s)
A bit more info; material cost is not an issue, this is a new house installation, the job is in BC Canada. I have attached drawings of the layout and the house floor plan, all one story. I have a permit but the town building inspector also does the plumbing inspection so I want the installation to be as plain as day as I question her abilities. Just for clarity, I have omitted the installation of cleanouts and fitting choices which will be "Y" fittings for drains and "T" fittings where the trap arm and venting is connected. This will include the Manifold that will be in the 6 inch wall cavity. There is limited access to the attic so this is why I have joined all the vents below the top plate of the water wall. What I am looking for is a vent system that is easy to follow and that will also pass the inspection. Everyone's comments will be appreciated. Thanks

TheEplumber 02-24-2012 11:27 PM

I don't know BC code but the changes I would make are:
Both toilets can be served 1-3" stack using an approved back to back fitting.(fixture cross)
Lav #2 would waste into the combined 3" toilet vent above the floor(vert. wet vent) thereby eliminating the vert. lav vent on #2.
#3,#4 toilets common vent should be 3"
#1 vent can be 1 1/2" until the common toilet vent
Tub and shower can also share a common 2" stack, 2" santee to the shower with a 2x1.5x1.5" santee to the tub- both served by a common 1.5" vent back to the 3" vent stack
I just saved you 3 waste risers through your floor :)
I can only put 3 toilets on a 3" line. Hopefully there is only one more on that building drain.
I hope this makes sense. I'm sure more plumbers will chime in. Maybe one that knows your code.

Sammy 2 02-25-2012 08:23 AM

Thanks for the feedback. There are only two water closets on this system as drawn. I have read BC plumbing codes. One section 7.2.4.1 says you can't use a cross fitting in a drainage system and 7.2.4.2 says a double sanitary T fitting shall not be used to connect the trap arms of water closets installed back to back. These items I understand and I am reading this to say that I could use a double Y fitting as you say but I really need to be sure my drains are straight forward in design ( also avoiding wet venting ) as I have a plumbing inspector who "only" goes by what she reads in the code book and if the book is not clear then she tells me to contact a qualified plumber for clarification. :eek: Anyone else have comments ?

VIPlumber 02-26-2012 11:26 PM

E-Plumber makes a number of excellent suggestions, and his advice is accurate in relation to the BC Plumbing Code.

Wet venting is part of our code, and is pretty straightforward. You shouldn't have to dumb down (simplify) your drainage and venting system just because the inspector doesn't understand.

Know your code references going in, makes copious notes, and you'll be well prepared to fight the inspector with the plumbing codes to back you up.

Good luck and let us know how you get on.

Sammy 2 02-27-2012 09:36 AM

A bit more ; is it a code requirement that the 4 inch main drain needs to stay that size at least until it reaches the main stack. To reword the question : At what point can I downsize the 4 inch main drain to 3 inch pipe ? Thanks.

TheEplumber 02-27-2012 11:44 AM

Quote:

Originally Posted by Sammy 2 (Post 864678)
A bit more ; is it a code requirement that the 4 inch main drain needs to stay that size at least until it reaches the main stack. To reword the question : At what point can I downsize the 4 inch main drain to 3 inch pipe ? Thanks.

This is really a code question that is specific to your authority having jurisdiction(AHJ). For instance- Idaho requires min. 4" exiting the house even if the total drainage fixture units can be served by a 3" drain. So we pipe 3" up to the foundation, then increase to 4" under the footing and outside 2'. However, I can cross the border into Washington and pipe according to the fixture load. I have stubbed out 2" before as the main drain size- no toilet of course.

The cross sectional area of your vents must equal the size of your building drain. So if you have a 3" (7.065sq.in.)leaving the house, you add up the sq. inches of the vents. They should be at least 7.065 sq in.
Some areas do want the 3 or 4" stack to vent full size thru the roof, though I hardly ever do. I size DWV lines according to the fixture load.
Hope I gave the answer your looking for


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