At a big home store today, all the black drain pipe was 'cellular core ABS' in 'schedule 40'. What does the 'cellular' mean? The pipe was very inexpensive.

  • Apparently cell core can be allowed above ground as it is "quieter" or the like: terrylove.com/forums/index.php?threads/cellular-core-abs.6866 but don't know too much about it :)
    – rogerdpack
    Commented Feb 16, 2016 at 22:07
  • 2
    Do "foam core" and "cellular core" mean the same thing? Commented Feb 17, 2018 at 12:27
  • Use solid wall pvc pipe instead,it is available in most jurisdictions and you can get dwv pattern fittings in pvc as well. Commented Nov 2, 2018 at 0:25
  • Supply houses in my area have never even heard of solid ABS pipe: all they stock is foam core. It's non-freezing area, but still...
    – Bryce
    Commented Nov 2, 2019 at 5:37

2 Answers 2


What you have is not solid. There's a foam or cellular interior to the pipe with two thin layers of sold ABS on the outside.

  • It costs less and weighs less than solid pipe. Thus it's popular at home stores that compete on price.
  • Not every jurisdiction allows use of cellular pipe. However it's common in the USA.
  • You need to be careful about backfilling such pipe with sharp rocks, which can pierce the thin shell.
  • When gluing, it's a good idea to coat the ends of the cut pipe, as the foam can and will slowly transport air and water (for the same reason, this pipe is never suitable for pressure applications).
  • You can't use it for pressure applications: this is meant only as drain pipe.
  • The pipe is fragile if dropped (take a section and stomp on it, chances are it will shatter into fragments, where a solid pipe would just hurt your foot).
  • It's more flexible than solid pipe, which is good in some cases, but causes sagging in others.

Here's a picture from a pipe vendor, where the foam core has been made white to show the detail. The pipe I've seen in stores all has a black core that mimics solid pipe at first glance:

Cellular Core ABS Pipe

Look around you'll see various opinions on the stuff. Some plumbers say they love it because it brings them repeat business. The vendors all claim various advantages to the pipe.

It's definitely not good in freeze/thaw weather if the ends are exposed (as they might be for a drain waste vent, or the end of a drain pipe run).

Foam core is regulated by ASTM F-628 Foam Core, and ASTM D-2661 for solid pipe.

Here's video on bursting of such pipe: https://www.youtube.com/watch?v=tWoTGu5s1Ys

  • What do you use instead? How do you get it?
    – Bryce
    Commented Oct 20, 2018 at 20:56

Cellular core seems preturnaturally disposed to warping. Not much worse things can happen than a belly in a sewer line. As I am not a professional whose livelihood depends on call-backs and regularly revisiting a jobsite to re-snake the sewers, I will eschew the use of this inferior so called product. YMMV😸

  • What do you use instead? Will you use ASTM F-628 pipe for vents?
    – Bryce
    Commented Oct 31, 2019 at 19:27
  • 1
    @Bryce you have the makings of a whole new question there, but as was mentioned in a comment on your OP use "regular" solid white PVC Schedule 40 pipe. This stuff may be cheaper, but regular Schedule 40 ain't expensive. At my local big box store, it was $4.17 for a 10' section of 1 1/4" pipe (literally bought some last night). Cheap enough that I'm using it for non-plumbing purposes.
    – FreeMan
    Commented Oct 31, 2019 at 20:00
  • Then what would you use for drain waste roof vents? PVC and sunlight don't mix very well either.
    – Bryce
    Commented Nov 2, 2019 at 5:36

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