PVC to Sillcock - Best Way?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by TipsMcStagger, Mar 5, 2013.

  1. TipsMcStagger

    TipsMcStagger Member

    Messages:
    31
    Location:
    NYC & FL
    I just built a small lean-to and had a 3/4" PVC pipe roughed-in up through the slab. I want to go through the wall (1/2" PT plywood with lathe and stucco on the exterior) to install a sillcock. I'm not sure about the best way to do this. I thought about transitioning the PVC to galvanized but decided that's probably not a good idea. I don't want to risk the PVC female adapter splitting. Should I transition to copper?

    Since PVC, galvanized, copper, etc. have virtually no "give" I'm not sure if I should attempt to have the sillcock flange rest flush against the exterior or if I should plan to have it extend two or three inches. I will place a block of wood between the stub-out and the stud so I'll have something to strap it to on the inside of the shed but I'm concerned that an errant tug on a fully extended hose could cause problems if the sillcock isn't well secured.

    Thoughts?

    TIA.

    Tipsy

    Water 3.jpg

    Sillcock.jpg

    I
  2. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    this isn't really going to answer your question, but you really shouldn't use PVC for water distribution, unless its CPVC. I can't see enough in the pic to tell...
  3. TipsMcStagger

    TipsMcStagger Member

    Messages:
    31
    Location:
    NYC & FL
    It's regular PVC. It's only going to supply a garden hose.

    Tipsy
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    Regular PVC is not rated for the pressure of a supply system! While there is a version of PVC designed for water supply, it looks like that is schedule 40, which is designed and tested for drainage only.

    Most silcocks are designed to be screwed to the exterior which holds the valve firmly in place. PVC becomes brittle with age and UV exposure. If it's the right type, once inside the building, you must convert to an approved pipe such as pex, cpvc, copper. If this is NYC, hopefully, you provided a means to drain the line, as in a leanto, that pipe will shatter in the winter when the water freezes making a real mess of things.
  5. TipsMcStagger

    TipsMcStagger Member

    Messages:
    31
    Location:
    NYC & FL
    It is SCH 40 PVC. I realize PVC is not rated for hot water but unless I'm missing something obvious, every house in this neighborhood is plumbed incorrectly. My home, as well as the neighbors all have regular Sch 40 PVC feeding from the main into the house.

    It's FL. No freeze concern.

    Tipsy
    Last edited: Mar 5, 2013
  6. mtcummins

    mtcummins In the Trades

    Messages:
    380
    Location:
    Pittsburgh PA
    If this were my project, I'd cut off that PVC line in the shed, bust out just enough of the floor to dig out the elbow, and then go inside and cut out the PVC from that end. This should leave you with a straight run of 3/4" pvc. Fish a 1/2" pex line through this, which will be a little challenging to make the 90 turn up into the wall, but otherwise you'll have a proper install w/o tearing out all of what you've done so far.

    If you happened to have used a long turn 90, or possibly even with a medium 90, the pex may slide right through the fitting with a little bit of lubrication on the pipe.

    You don't need 3/4" for a garden hose, the hose won't flow much more than you can get through a 1/2" anyway. But you'll have a properly done install. If there's going to be a lot of stuff shoved in and out of this shed, you might want to put some kind of sleeve, like PVC, over as much of the exposed pex as you can to protect it from damage, and UV (will break down Pex over time).
  7. TipsMcStagger

    TipsMcStagger Member

    Messages:
    31
    Location:
    NYC & FL
    Not really sure I follow but this is a brand new slab built to FL hurricane code. The footer is 18" wide and 16" deep with #5 rebar. I'm not breaking up my new slab.

    If there's a way to transition from PVC to PEX, I can do that inside the shed. It'll only be a foot or so. This will be covered with OSB and I'll fabricate a hatch, should I need to access this in the future.

    Tipsy
    Last edited: Mar 5, 2013
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    I can't tell from the picture...is the pvc sleeved through the slab, or is it in direct contact with the cement? The relative differences in expansion/contraction between the two materials will stress crack the pvc over time. PVC expands MUCH more with a rise in temp than concrete.
  9. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington


    Yeah.............India was like that too. I drank bottled water there, and wouldn't touch it unless the cap was still on it.

    PVC is allowed underground for cold water. Being underground keeps it in the safe range.
    If you have it above ground, it's getting warmer and loses it's strengh. I realize that a few bucks is a lot of money for someone living in Florida.

    When converting from plastic to threaded, you always have a male side for the plastic. A female plastic fitting will split.

    The hosebib should be secured to the shed.
    Piping is never strong enough for support.
    Last edited: Mar 5, 2013
  10. TipsMcStagger

    TipsMcStagger Member

    Messages:
    31
    Location:
    NYC & FL
    I didn't mean to imply houses in this neighborhood use PVC for hot water. Only that all of the homes have PVC, underground, feeding from the main to the house, where it transitions to copper. This home had a slab leak prior to my ownership and had been replumbed with CPVC through the attic.

    I'll have to ask the builder why he deemed it acceptable to have the PVC in direct contact with the slab.

    Thanks.

    Tipsy
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    quote; you really shouldn't use PVC for water distribution, unless its CPVC
    quote; Regular PVC is not rated for the pressure of a supply system! While there is a version of PVC designed for water supply, it looks like that is schedule 40, which is designed and tested for drainage only.

    I don't know where these guys are getting their information, but PVC is PERFECTLY okay for water distribution, (MOST of houses in this area have PVC water lines from the meter to the building), but only outside the building where a failure cannot cause damage. AND sch. 40 is what is used for "pressure" water systems. You should never use metal into a female PVC adapter because ANY corrosion will create stress and crack it, while a male PVC adapter is one of the weakest fittings made and WILL crack at the thread. Use a coupling and half of a PVC nipple glued into it, then transition to a copper female adapter. From there, you would install the hose faucet just as if the whole thing was copper with the piping secured against any stress or movement.
  12. TipsMcStagger

    TipsMcStagger Member

    Messages:
    31
    Location:
    NYC & FL
    Thanks. I'll transition to copper and properly secure the sillcok to the wall.

    Can't say I'm exactly happy knowing the PVC should have been sleeved through the footer but there's not too much I can do about it at this point.

    Tipsy
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    Actually, according to code, it should not even BE in the footer. It should have transitioned to an "interior approved" materia, i.e., copper, CPVC, PEX, etc., l outside the building.
  14. TipsMcStagger

    TipsMcStagger Member

    Messages:
    31
    Location:
    NYC & FL
    Thanks. Just for my own education, that applies to outbuildings as well? This is a lean-to shed. It's against the house but not accessible from inside the house.

    Tipsy
  15. Terry

    Terry Administrator Staff Member

    Messages:
    15,416
    Location:
    Bothell, Washington
    hj should have said "building"

    Code doesn't care what size the building is. What's good for the goose is good for the gander.
  16. TipsMcStagger

    TipsMcStagger Member

    Messages:
    31
    Location:
    NYC & FL
    Got it. Thanks.

    I tried to piece this together today based on HJ's advice but hit a roadblock at the PVC nipple. The only PVC nipples I could find were an Orbit irrigation nipple (seemed to be thinner than Sch 40) and a Sch 80 nipple. Not that I hold the guys who work in the home centers in the highest esteem but I was told by one gentlemen that Sch 40 PVC nipples don't exist.

    Tipsy
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,319
    Location:
    New England
    Glue a male threaded fitting onto the pipe stub, then use a female copper fitting on it.
  18. TipsMcStagger

    TipsMcStagger Member

    Messages:
    31
    Location:
    NYC & FL
    I had those components in my hands but based bold and italicized comment in the below quote, I thought I should seek more advice prior to moving forward.

    Tipsy

    Last edited: Mar 6, 2013
  19. DavidSeon

    DavidSeon New Member

    Messages:
    47
    Location:
    MS Gulf Coast
    Wait for the plumbers' advice to be sure, but I seem to remember that PVC Sch 80 nipples are used for both Sch 40 and Sch 80 fittings (same o.d. and threads maybe?).
  20. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    quote; that applies to outbuildings as well?

    It will be just a "destructive" to fix under an outbuilding as it would be in your house. You use a sch. 80 threaded nipple cut in half, sch. 40 would be too thin to make a "substantial" thread. A "sleeve" around PVC pipe under a concrete floor does NOTHING, except give you one more layer of pipe to go through to reach the broken pipe or fittings.
    Last edited: Mar 7, 2013
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