Return to the Plumbing Forum | Post a Follow-Up

PVC drainage under concrete

Posted by bettydiy (My Page) on
Sun, Oct 11, 09 at 9:56

While installing a bathroom in my basement my boyfriend tore out the concrete floor and ran PVC drainage pipe into the existing cast iron drainage pipe. He then reconcreted the floor. I recently found out that this may be a code violation. Is there any physical reason for this? Can the pipe not withstand being underground due to pressure or weather related reasons? I live in Philly so the weather is all over the board. Anybody have any ideas?

Thanks a lot,

Follow-Up Postings:

RE: PVC drainage under concrete

Who said it was a code violation??

What specifically was said to be in violation, or wrong?

Here in Seattle, 'Fernco' couplings are used all the time. A rubber boot, with stainless steel clamps; is used to join pvc to cast iron. If not buried in ground - then you have to use the same thing - except that it has an entire stainless steel cover sleeve over the rubber - in addition to the clamps. Keeps the rodents from chewing the rubber...

So what was the problem? The fact the work was done without a permit??

If you just stuck the plastic into the cast iron - and didn't use a coupling - that would be a violation...

I live in Seattle, not Philly...

Here is a link that might be useful: Fernco Couplings

RE: PVC drainage under concrete

There ARE direct (threaded) PVC-to-Cast Iron couplings that do NOT involve rubber, and thus are not vulnerable to rodents, and meet code in every way. That said, IIRC, to be buried under slab, it can't be just any PVC, but must be Schedule-40, or maybe even Sched80.

As mentioned above, your BF may know his plumbing well, and your new drain will work fine and last long, and the only "violation" is that you did not cross the palms of the various parasite bureaucracies there in Duh Demokratik Peep-uls' Republik of Silly-delphia. ;')

RE: PVC drainage under concrete

"There ARE direct (threaded) PVC-to-Cast Iron couplings..."

There is not a lot of threaded cast iron around.
Rubber slip seals, oakum and lead on older stuff, or no-hub with rubber and stainless clamping.

There is a ton of threaded steel pipe, but it is rarely used in residential over a couple inches.

Since the minimum line for a toilet is 3 inches, it is not very commonly steel.

RE: PVC drainage under concrete

QUOTE: "to be buried under slab, it can't be just any PVC, but must be Schedule-40, or maybe even Sched80."

WRONG!!!! You may NOY use PVC sched. 80 pipe to make a drain line.

Whenever we hear the word "schedule" we generally think in terms of time, by example, when you make out a personal schedule you are making a list of events in your day, generally regulated by time, but in fact, the word "schedule" actually means "A list".

Understanding that pipe is made for many different industries and applications it then stands that they must make pipe with differing wall thicknesses to withstand the differing working pressures or physical stresses that may be encountered.

Officially Pipe is measured by its ID (inside diameter) while tubing is measured by its OD (outside diameter) however technically speaking all the measurements are said to be "Nominal Trade Sizes". This means that while a piece of pipe meets the needs of a specific size, the actual internal diameter may vary slightly, depending upon the wall thickness of the pipe. It is done this way so that we may have a standard set of taps and dies to cut the threads on all pipe, regardless of wall thickness, otherwise we would need a separate set of taps and dies for every variation in wall thickness.

Iron Pipe, PVC Pipe and ABS pipe are made to the Iron Pipe Standard (IPS).

Under the IPS we have separate lists (schedules) that give the full dimensions plus temperature and pressure ratings for the differing wall thicknesses of the pipe. Basically, the higher the Schedule Number the thicker the pipe wall.

PVC pipe intended for pressure piping applications is approved under the American Society of Testing & materials standard ASTM-1785 made in sizes 1/4", 3/8", 1/2", 3/4". 1", 1-1/4". 1-1/2", 2", 2-1/2", 3", 3-1/2", 4", 5", 6", 8", 10", 12", and 18" to wall thicknesses defined in sched. 20, sched. 30, sched. 40, sched. 80, sched. 120 and in some rare instances sched. 200.

PVC pipe approved for DWV (drain, waste & Vent) applications is made under ASTM-2665 and only includes Schedule 40 pipe in sizes 1-1/4", 1-1/2", 2", 3", 4", 6", 10", 12" & 18".

All PVC schedule 40 pipe that is approved for DWV application will have both ASTM-1785 & ASTM-2665 printed on the pipe wall.

All installers, both professional and DIY should be made aware of this because under the general rules in the Plumbing Codes it expressly states that PVC pipe MUST BE installed in such a manner that the listing on the pipe wall can be readily seen by the inspector. If you happen to install a pipe where the listing is positioned against a wall or joist or upside down in a trench where the inspector cannot see the writing, he or she would be well within their legal authority to red tag your job, and I have encountered some inspectors that not only will red tag it, they don't give you a reason why, other than to say the pipe is installed incorrectly.

RE: PVC drainage under concrete

My bad...

SO... will Betty's house be floating away on a river of sewage? ;')

RE: PVC drainage under concrete

Providing the pipe is schedule 40, labeled as approved for DWV under ASTM-2665, all joints properly made up with cleaner & glue and the pipe is buried in the soil beneath the concrete she has nothing to be worried about.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Plumbing Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here