# Foam Core PVC disaster



## Bill

Got my R/I done yesterday and let everything set overnight to seal up good. Tested the DWV today and kept getting a pressure drop of about 1lb per minute! Unusual for me as I always insist on priming the whole hub including the lip in back and on top. I even insist that the 1/4 inch edge of the PVC pipe be primed as well. This creates 3 seals, end of pipe to hub, flat of pipe to socket, then when I smear the glue after joining pipe it fills in any voids from the lip of the hub to the pipe. So for the life of me I could not find the leak. Finally found it at a Sioux Chief test type closet flange. Figured the seal was cracked from someone dropping it or from delivery. Broke the test cap off and stuck a 3" inflater ball in the riser. It still lost pressure. This time I added water on top of the ball and no leaks, but I could hear air. Filled the pipe above the ball to the top of the closet flange and noticed that the bubbles were in fact coming from the edge of the pipe itself! I figure its because the air is getting between the 2 layers of PVC at the tee wey and traveling up and out the top of the pipe. I have NEVER in my life seen this. I always use foam core pipe as thats pretty much what most suppliers carry here. For now on any riser to my toilets will be done with sch 40 solid PVC and not foam core:furious:


----------



## greenscoutII

I used to think foam core leaks were a myth that production plumbers believed in to excuse sloppy joints.:laughing: That is until I had one........

It seems to be a cold weather phenomenon. I think if it's cold enough the layers of PVC can develop a crack from being stepped on, dropped, flexed too much, etc.

Doesn't seem to happen all that frequently though, so maybe doing it all in solid is overkill? It certainly won't hurt anything, I just prefer foam core as I cut pipe with a roll cutter.


----------



## easttexasplumb

I had never seen a leak in a pvc drain untill I started using foam core pipe.


----------



## gitnerdun

Foamcore all the time no problems here. I have had problems getting test balls to seal in the pipe and flanges that fit too loose in the pipe, thus leaking sewer gas later. That was tough to find.


----------



## para1

Foamcore above slab only.:thumbsup:


----------



## Proud Plumber

I have wondered about it for a long time. Particularly UV damage to foam. So many commercial specs wont allow it. I live in a production home mecca and it is used widely.

Although it cuts like butter.


----------



## Tommy plumber

I heard of a contractor here that used foamcore for the W/C risers on the second floor of some townhomes. After townhomes were occupied, residents noticed leaking in the ceilings below the bathrooms. It was traced back to the 4" pvc foamcore risers for the toilets. Somehow when toilets were flushed, some of the water wicked out of the pipe and was dripping down below. 

Foamcore is great......if you're a service plumber :thumbsup:


But it bites real hard in the rear-end.....if you're a new construction plumber who has to warranty the stuff


----------



## Epox

I dug up a sewer line once to install C/O's. I started to saw the pipe with sawzall and with just a inch of cut apprx, it cracked the full circumference on it's own with a loud pop. It apparently had stress on it. After that I worry bout cellcore DWV. I can't say I've had a leak issue any more than sch, 40 but I worry about it holding in the future. And no was not on a cold day.


----------



## 6th Density

Too many times have I seen the G__ Damn supply house deliver material (pvc pipe) by just dumping it off the truck without a care in the world. Doesn't really matter right... Wait till it's 30 to 40 degrees outside or less even if it's sch 40.

Point being stay away from the foam crap. You never know how the suppliers handled your product. Don't forget it's going to be in somebodies house for the next 50 years!!!


----------



## 422 plumber

All the manufacturers call for beveling the end of the pipe, do you?


----------



## Epox

jjbex said:


> All the manufacturers call for beveling the end of the pipe, do you?


Rough-ins i do. I use chop saw to cut and then bevel.


----------



## sparky

para1 said:


> Foamcore above slab only.👍


Agreeee,foam core is hard to get the pitch right because it's so flimsy,I do drains out of sch 40 and vents with foam core


----------



## Tango

If those fragranced essential oils are poured down the drain and come into contact with the foam core the pipe will crack in dozens of places like tiny veins in a red eye and leak at every fissure.


----------



## Plumbus

Using two different types of PVC sounds like a logistics headache. PVC 40 all the way for me.


----------



## OpenSights

Plumbus said:


> Using two different types of PVC sounds like a logistics headache. PVC 40 all the way for me.


Not 3” 30 for newer homes? Drywall guys must hate your guts!


----------



## Plumbus

Not sure what you mean by "3" 30".


----------



## OpenSights

Plumbus said:


> Not sure what you mean by "3" 30".


3” schl 30


----------



## skoronesa

OpenSights said:


> 3” schl 30


Schedule 30 is not a thing as far as I know. Plumbus was saying he only uses schedule 40 pipe, not that he only uses 4" pipe. 

I agree that foam core is garbage. If you're going to use foam core you might as well go full hack and use abs. I've said it before and I'll say it again;

Schedule 40 PVC, the superior white pipe.


----------



## OpenSights

I never minded working with ABS, but that was over 20 years ago.... so....

40 doesn’t fit in 1.5x2.5” walls very well.


----------



## skoronesa

OpenSights said:


> I never minded working with ABS, but that was over 20 years ago.... so....
> 
> 40 doesn’t fit in 1.5x2.5” walls very well.


What are you talking about? Even DWV abs or foamcore pvc is still "schedule 40" in size, it just doesn't meet the other requirements of the schedule 40 specification.

Are you running 2" pipe in those walls? Or are you talking about CTS plastic pipe? Even CTS 3" pipe would be 3-1/4" on the OD so it wouldn't fit.


----------



## OpenSights

skoronesa said:


> What are you talking about? Even DWV abs or foamcore pvc is still "schedule 40" in size, it just doesn't meet the other requirements of the schedule 40 specification.
> 
> Are you running 2" pipe in those walls? Or are you talking about CTS plastic pipe? Even CTS 3" pipe would be 3-1/4" on the OD so it wouldn't fit.


Extremely rare that we run 3” schl 40. In walls 3” schl 30.


----------



## skoronesa

OpenSights said:


> Extremely rare that we run 3” schl 40. In walls 3” schl 30.


Well spank my azz and call me sally. I never heard of it being called schedule 30. We would call that CTS because it's the same size as copper pipe. It's also the same size as Ti-Krome Tubotron!!!!


----------



## sparky

Plumbus said:


> Using two different types of PVC sounds like a logistics headache. PVC 40 all the way for me.


I like foamcore cause it cuts so easy with ratchet cutters if it's fairly warm,ratchet cutters won't hardly cut sch 40 pipe


----------



## sparky

OpenSights said:


> Extremely rare that we run 3” schl 40. In walls 3” schl 30.


Never seen 3" sch 30 pvc,we have sch 35 but it's not legal to use inside a house or blding in Kentucky


----------



## OpenSights

sparky said:


> Never seen 3" sch 30 pvc,we have sch 35 but it's not legal to use inside a house or blding in Kentucky


Interesting. Schl 30 is very common here.


----------

