Schedule 40 PVC vs. Schedule 40 Foam Core

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by ROSSBYINGTON, Apr 9, 2008.



    Apr 9, 2008
    My wife and I are building a house. The builder(gen'l contractor) was instructed to use Schedule 40 PVC and now we see there is Schedule 40 Foam Core in the house (including the exterior waste lines). The walls are not yet closed. The builder & plumber said that Foam Core is they typical product of choice and that we shouldn't worry about it. I called Charotte yesterday and asked the rep. if he was building his home what would he use and the answer was Schedule 40 PVC.

    What do you think? Are the two pipes of equal quality? Are we being to picky? This is an expensive custom house that, until up till now, has been built beautifully (both structurally and visually).

    Thank you in advance.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    Schedule 40 is a measurement, not the pipe's quality. All sch.40 pipe will have the same i.d. and o.d. which means the wall thickness will be the same. That has nothing to do with HOW the pipe is made, i.e. solid core or foam core. We do not use PVC drain lines here, but where it is used, foam core seems to be the material of choice for drain lines. But it is not a "pressure" material so it is not used for supply water lines. If it were a problem for you, your specification should have called for scheduler 40 pressure rated piping.
    Last edited: Apr 9, 2008
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    I'd call the manufacturer for thoughts. My gut feel is that the foam core stuff is more susceptable to getting crushed underground under adverse conditions - it isn't as strong (but might be more flexible which could help - I don't know, this is a guess). Those shouldn't happen, but could. Inside the house, I wouldn't have big problems with either, it is only outside I'd have to give it a second thought.
  5. cab

    cab New Member

    Aug 23, 2007
    Not sure but I hear it is against code in WI to use foam core pvc in the dwv lines....


    Apr 9, 2008

    Thanks for the help. I called the manufacturer again today and the tech was extremely confident that the foam core would work fine. I also spoke to the local inspector who was also sure it would work properly.

    My frustration is that the foam core was not specified but installed. Do I win the battle (by having them spend the time and money replacing it) and possible lose the war when the project grinds to a halt. GC omits to the mistake but has not really come up with a solution.

    Dazed and Confused in DC who now knows more about PVC pipe than I ever thought I would.

  7. rombo

    rombo New Member

    Mar 30, 2008
    i wouldn't worry about
  8. leejosepho

    leejosepho DIY scratch-pad engineer

    Nov 23, 2006
    disabled-retired industrial fabricator
    200 miles south of Little Rock
    Same here. I first saw it when the regular stuff was scarce right after Katrina, and I have used it both inside and outside without problems.
  9. Lancaster

    Lancaster New Member

    Nov 7, 2005
    Here's how I see it.You could request the materials price be reduced by the difference between the pipe prices.But if you did that,you would probably have to absorb the recent large increases in PVC cost.So it would basically wash out anyway.
    I say no harm,no foul,let it slide.
  10. tjbaudio

    tjbaudio Sound and Light Suppervisor for a School District

    Dec 6, 2005
    sound and light suppervisor for a school district
    As long as there are no long unsupported lines the your fine. This would hold true for any material. I have the foam core stuff and it is not a problem. If the building inspector is happy let it go. It will not affect the value of the home any way.
  11. fozzy12

    fozzy12 New Member

    Jan 31, 2008
    quality manager
    North of Detroit, MI
    Foam core PVC

    Let it slide, it isn't affecting anything. The GC admits it was a mistake, he knows you're paying attention. He will probably be a little more careful in the future. No sense starting a needless war if you like what he's done so far.

  12. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Aug 23, 2005
    I&C Engineer (mostly WWTP)
    Columbus, OH
    Let it slide inside, but check the city code to see if you can use it outside underground.

  13. Dunbar Plumbing

    Dunbar Plumbing Master Plumber

    Apr 18, 2005
    Service Plumber, Outdoor Temperature Relief Owner
    Northern Kentucky/Greater Cincinnati Area
    The only performance issues I've seen with the product is how you have to lip the ends of the pipe with glue and cleaner when preparing the solvent weld joining method to prevent an air test failure.

    Meaning, if you don't consider this practice you'll have problems with getting air tests to properly hold for inspections, due to the fact that air can travel through the piping walls.

    I guarantee your plumbers did this to protect this situation from happening, otherwise they know the fix. Tear it out!

    When foam core came out eons ago, we were told to make this a common practice in order to get air tests to hold 5 pounds of air.
  14. rdtompki

    rdtompki New Member

    Dec 21, 2005
    I'm a bit confused about the part of the original question that talks about the PVC being inside the "walls" or is the original question only referring to drain and waste in the walls vs. potable water?

  15. BAPlumber

    BAPlumber Plumber

    Jul 18, 2007
    Journeyman Plumber, business owner
    Vashon, Washington
    It sounds like the GC did what he was instructed. He used Sch. 40 PVC. If he was instructed to use Sch. 40 Solid Core PVC and didn't, then there may me a problem. The pipe will work fine, it just isn't what was contracted for.
  16. Tattors

    Tattors New Member

    Mar 17, 2009
    when a snake tears away, or rubs, while cleaning; then the exposed foam will be exposed for failing and one will wish they had not shaved a few bucks off for a better builder bottom line..... Foam core is a time bomb that has solved the problem of pvc line invincibility. sweet
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