I plan to have a house built, and circumstances (financial and otherwise)
necessitate that I assume some of the construction chores such as plumbing,
electrical, floor plan design, and contracting. I'm probably way over my
head on the plumbing task because I've had very little experience. The house
will be on a slab foundation and I'm considering using under slab PEX tubing
rather than copper due to corrosive soil conditions. I'll use above slab
distribution manifolds (hot & cold) to route under slab PEX lines to remote
areas and connect them to mini-cpvc manifolds for cpvc linkage to fixtures in
each respective remote area. My first pass to the DWV system is pictured
in the link below.
The 4" waste line will slope @ 1/4" per ft for about 30' for a 7.5" drop. The
upper end of the 4" main will have to start about 6" low to accommodate
the kitchen sink slope span.
I'm sure its amateurish and inconsistent with professional methods,
but I would like to know if there are any glaring red flag issues ?
Any comments on the supply and DWV system would be appreciated.
(Note : I'm in a remote area and no local plumbings are in force)

Attached Images

 

speedball1

If elevation will be a problem you may reduce the slope of the 4" main to 1/8" per foot. Move the main over so it doesn't run directly under the toilets and showers and connect from the side. You will save at least 8 to10 inches of elevation if you do. Increase the kitchen sink drain to two inches, no 1 1/2 " under the floor. `1 1/2" is asking for trouble. On the shower next to the laundry room (5) move the vent from downstream of the shower to the right hand wall so it ties in upstream from the shower drain. you can not discharge a major fixture past a unvented minor one and that's what you're doing in the present layout. Same for shower (6). Move the vent so it's upstream from the drain.
Increase the lavatory drains to 2". What is #4 fixture and why do you have two vents side by side when you're close enough to wet vent (4) to #(3) drain? More questions? I'm as close as a click. regards, Tom

Lee999

Thanks for your input. I made the changes to the drawing as shown
below. Fixture #4 is a utility sink. I dropped the local vent and now
show the drain connecting with the lavatory drain line. Have I corrected
the problems ? One other question - drain and vent pipes that run vertically
in exterior walls through the foundation slab are over the slab footing. How
are these pipes handled with regard to the 12 to 18 inch deep footing ?
Thanks, Lee

Attached Images

 

speedball1

Good morning Lee, The drainage looks a lot better. Just one thing. How far is it from the washer trap,(2) to the lavatory vent (3)? On a 2" line you are allowed a 5' line between trap and vent. Anything over that and you have built youself a "S" trap which is outlawed in all codes.
The exterior vents are a different story. When we rough a slab there are usually two blocks laid over the poured foundation before the rough goes in and the slab's poured.. if we have exterior vents we just break out the block and put the vent in the wall that way. When the slab's poured the vent's are up through the slab and inside the wall. If the block masons leave you two blocks over the poured foundation you should have no problem with elevation. To figure your developed length take the 36 foot length of the main and add the distance from the kitchen sink to where it ties to the main. that will be your developed length. I always add 6" to my drop when I figure slope just in case I make a mistake. sort of a safety net. I've seen plumbers that started their rough from the low end and by the time they've reached the furthest fixture they're up out of the slab. Always start your rough from the furthest fixture, give yourself 6 inches of "wiggle room" and you're gonna be fine. cheers, Tom