Roughing in small job in shop

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by nmlaz, Oct 30, 2011.

  1. nmlaz

    nmlaz New Member

    Messages:
    8
    Location:
    Vancouver, WA
    Hello,

    I'm roughing in a toilet and two sinks in the upstairs of my shop. The sinks will share a common wall (one in bathroom one for bar).
    I will have a small WH (4gal) that will likely be in a cabinet under a sink. I have 3/4" PEX stubbed in downstairs wall. I figured on installing a shutoff where it enters shop and continuing with 3/4" PEX up through framing and through attic of shop which would amount to 10 vertical feet and about 40 horizontal feet.
    From here, I'm trying to figure out the best way to plumb with hot water to 2 sinks and cold to both plus a toilet.
    -Should WH be before a manifold or one branch off of it?
    -Should I just skip manifold and just 'T' off of main line to catch both sinks, WH and toilet?
    Water demand should be pretty low. I am probably over analyzing this whole project. My next over analyzation will be with the waste pipes...coming soon.

    Thanks for any help.

    Nick
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,510
    Location:
    Cave Creek, Arizona
    Usually you "analyze" the waste and vent pipes, then fit the water piping around them. Absolutely NO reason to use a manifold.
  3. nmlaz

    nmlaz New Member

    Messages:
    8
    Location:
    Vancouver, WA
    Thanks. Waste is not that big an issue though hoping to use one vent for both sinks and toilet. Ive read using 1-1/4" pipe for sinks gives me 5' to vent 1.5" = 6' etc. Toilet will be main line into main trunk with sinks likely to 'Y' into it.

    Is the distance in pipe length i.e incorporating fittings, traps, sweeps etc?
    Also if vent is in 1.5" line from sinks will it be adequate for toilet if it is before 'Y' into 3" line? (Example: toilet has about 6' to trunk which is vertical pipe run. The 'Y' would likely be somwhere in the middle of that which captured the sinks and likely 1.5" line... I was hoping vent could be in the 1.5" portion. Total distance from toilet about 6 to 8 feet.

    Thanks again.
    Nick
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,510
    Location:
    Cave Creek, Arizona
    I would NEVER use a 1 1/4" drain line for anything, and would not know where to find the fittings and pipe if I wanted to. Some areas require a 2" vent for the toilet and others 1 1/2" so it depends on your local code. HOW you connect the sinks to the toilet line will determine whether it is a proper vent or not.
  5. Terry

    Terry Administrator Staff Member

    Messages:
    14,904
    Location:
    Bothell, Washington
    In the state of Washington

    The toilet needs a 2" vent within six feet.

    A 1.5" trap arm needs a vent within 42" or three feet and six inches.

    You can wet vent the lav over the 2" toilet vent, but not the bar sink.
    The requirement is two pipe sizes more, which works with the lav.
    Since the bar sink requires a 1.5" min, bumping it two pipe sizes would be more then 2".

    Pipe and fitting are pretty cheap. It's a lot quicker for a plumber to use the right amount of fittings and pipe for this simple job.
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