# Pex Under Slab



## Plumberman

Down here they finally gave the go ahead to run pex under slab, use to be only roll copper. Saves on material for sure. Just about every HO on new builds are requesting PEX these days.


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## Ron

Pex with no fitting allowed here under a slab.


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## Plumberman

I thinking its been the norm up North for awhile it just finally passed down here. Like within the last year or so...


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## threaderman

I've got no problems running pex under -ground.Believe it or not,before I left Florida ,we were running cpvc under-ground in Pinellas county,which was legal [with fittings,not coiled].That to me is not a good idea,but we used to hydro-test to either 3 times the incoming pressure or 150 psi,not to exceed 150 psi.,crazy huh.So if you held that pressure for 24 hrs. like i used to, then you walk away pretty confident with the system.


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## Plumberman

It makes sense for the PEX since copper has skyrocketed over the past couple of years.


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## user4

Cook county requires all buried water pipe to be type K copper or ductile iron.


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## Plumberman

Killertoiletspider said:


> Cook county requires all buried water pipe to be type K copper or ductile iron.


Any C900?


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## 22rifle

Killertoiletspider said:


> Cook county requires all buried water pipe to be type K copper or ductile iron.



I get the feeling you just get way too much enjoyment out of posting your local requirements! LOL

But that's cool because like I said before, I really, really enjoy hearing about it.


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## user4

22rifle said:


> I get the feeling you just get way too much enjoyment out of posting your local requirements! LOL
> 
> But that's cool because like I said before, I really, really enjoy hearing about it.


Chicago's code is ridiculous in a lot of ways, but I also see why in a lot of ways. About a month ago a fireman in the suburbs was killed in a warehouse fire when a NH CI fitting fell from 40' and hit him in the head, the 6" wye broke his neck and killed him instantly. That is basically impossible with the hub and spigot joints that Chicago requires.


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## Plumberman

Killertoiletspider said:


> Chicago's code is ridiculous in a lot of ways, but I also see why in a lot of ways. About a month ago a fireman in the suburbs was killed in a warehouse fire when a NH CI fitting fell from 40' and hit him in the head, the 6" wye broke his neck and killed him instantly. That is basically impossible with the hub and spigot joints that Chicago requires.


Dang thats horrible.... I can see why they enforce that kind of code then.


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## Ron

Sorry to hear that. I guess wearing a hard hat was not a requirement.


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## user4

Ron The Plumber said:


> Sorry to hear that. I guess wearing a hard hat was not a requirement.


He was a fireman, and wearing his assigned headgear during an active fire.


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## Ron

Miss read that post, sorry man. :bangin:


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## Herk

I see no problems with PEX under a slab. Back when I was still doing houses, FmHA was requiring that all copper be in insulation. I liked that because it protected the pipe from grinding on coarse dirt. I should imagine that the same would be true of PEX - it would be a good idea to protect buried pipe with foam insulation up through the cement. If done well, it should even be possible to pull a new piece of pipe through it, maybe?

My biggest concern with PEX isn't the pipe - it's the thin brass fittings. So I don't think they should be buried. If the water isn't aggressive, it might not matter, but it's possible for the water to change over years, too. I could swear our water here is more aggressive than it used to be, based on seeing more pinholed copper.


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## 22rifle

I put 3/8" foam insulation on all my underground PEX. Of course, I did the same with copper too.


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## ILPlumber

pex and concrete must get along pretty well. There's a ton of it in slabs for hydronic heating.


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## 22rifle

ILPlumber said:


> pex and concrete must get along pretty well. There's a ton of it in slabs for hydronic heating.


It isn't so much the concrete as it is the material under the concrete I am concerned about. Of course, I sleeve all slab penetrations regardless.


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## ILPlumber

I agree. That can be a problem no matter what the pipe material. Our problem with pex in IL is we have to oversize the pipe due to the restrictive fittings. I never have used the stuff other than hydronics where it just loops out and goes back to the other manifold.


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## 22rifle

ILPlumber said:


> Our problem with pex in IL is we have to oversize the pipe due to the restrictive fittings.


To some extent, the concern over the restriction is over rated. 

That said, the Uponor or Rehau fitting systems eliminate that issue and in my opinion, is a selling point.


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## Mike Jessome

Herk said:


> I see no problems with PEX under a slab. Back when I was still doing houses, FmHA was requiring that all copper be in insulation. I liked that because it protected the pipe from grinding on coarse dirt. I should imagine that the same would be true of PEX - it would be a good idea to protect buried pipe with foam insulation up through the cement. If done well, it should even be possible to pull a new piece of pipe through it, maybe?
> 
> My biggest concern with PEX isn't the pipe - it's the thin brass fittings. So I don't think they should be buried. If the water isn't aggressive, it might not matter, but it's possible for the water to change over years, too. I could swear our water here is more aggressive than it used to be, based on seeing more pinholed copper.


 
Uponor fittings are actually made of hard black plastic which are ideal for underground, but that said, why would you have any joints underground in the first place bend support and just tape them to your stubouts until the house is framed and ready to be roughed in after the underground is completed


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## younger-plumber

pex under a slab kinda sounds iffy to me? idk y. lol. prolly a great idea.... it just comes off as a bad plan in fifty years....foam insulation does seem as a good insurance or even sleaving the pipe in pvc.


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## Kyle

up here we still have alot of options but mostly run with "Kitec" poly/alum/poly" and no fittings from street main to main shut off in house. never seen copper in new constructions. main service installers willl run it to under grade beam ( full basement up here in our igloos =) an leave plenty coiled. run out an before where penetration is goin we run the kitec through one size larger 90 degree long bend electrical fitting ( pvc) just allows for nice support when they are pouring the floor and never lets the penetration touch the concrete. use to see in the past that before we used the 90 fitting when they were screeting the concrete every now an then they would hit the kitec with the trowal... hell of a mess, with the fitting protects from that an looks good in the end.


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## Proud Plumber

Most all pex i have ever done is in the trusses. Several years ago I helped one of my bosses do is own house. He did it in Manabloc and looped the poly (back then) under the slab. However when put the dwv in the ground, we ran seperate case lines out of 2" and 3' pvc pipe under gound. At the 2nd rough we pulled the pex lines through. he was always concerned about failure. Therefoe by doing it that way he could always pull new lines easily. It was a pretty cool idea, the second rough went quickly.


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## Protech

Been runnin pex underslab for years. Gotta watch out for abrasion. Zip tie the sleeves shut so no concrete gets in your sleeves. Not allowed to putt fittings under slab unless they are polymer or De-zincified brass.


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## John Craig

Pex installed under slab has been in use for quite a while here in the Pacific NW . Its primary use for radiant floor heating. 


John Craig


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## Protech

I think the original post was referring to potable distribution.


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## Pipemaster

*I would definately sleeve the pex as well. 3 inch sounds good so you could pull a new run if you have too. Out here in California they wont let us bury pex yet, but we have talked about it, if sleeved.*

*Getting it past any inspection would be a nightmere. *

*We just finished a multi million dollar house out near Hollywood with PEX.*

*It's quiet, looks good, and easy to work with, we are doing another repipe on monday with it as well since the copper guru's want to rape us, and people are breaking into homes and jobsites to steal it.*

*Hahahaha Imagine a copper thief stealing pex :thumbup:*


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