I have a contractor who insists it is OK to embed PVC pipe in a concrete slab. This is regular white Sched 10 PVC, and will be used for irrigation water.

I have always heard that PVC is never to be in direct contact with concrete... must be sleeved. I have heard that concrete reacts with both PVC (makes brittle) and the glue in fittings (degrades PVC cement).

Which of us is correct? Even more important, can you refer me to a reliable document or source to back up your position?

Thanks Everyone,
BD

You are correct.

Twinkie,

Thanks for the speedy response (and for agreeing with me!). Do you have any idea where I might find a reference that spells out prohibition of "PVC directly in concrete"... I have looked all over the web with a bunch of search phrases... bupkiss. This seems small, but it is actually a very large issue on this project... thanks in advance for your help.

I've been in water treatment for 20 years, I've never heard that about PVC. I would be curious if somebody else knows something different.

I know you don't put cement in direct contact with metal pipes, since the ph in concrete will damage the pipes whether steel, or copper. Those pipes can be wrapped in sheet rubber, or a similar non-conductive material. I've seen other guys wrap them in "the handy man's friend", duct tape. I still prefer sheet rubber. :)

I'll be interested in seeing some of the other expert opinions.
Al

It is also up to what your local building codes allows. Some do and some don't. My husband used to work in concrete and he would know the answer but he dropped dead in 2002 so it's kind of hard to get a straight answer from him. Talk this over with the county inspector about this as you may have to do a different configuration to pass inspection.

I have never heard of a restriction against pvc in concrete but that doesn't mean it's not so.
Here are two references that imply that pvc can be used in concrete.
I looked at a lot of sites and didn't find any mentions against the practice.
Maybe you could check some building codes.


This one talks about a pvc material buried in top of concrete
Creative Polymer Industries Pte Ltd : Keyfoil PVC Liner

WIK PVC conduit
PVC conduit is the lightest in weight compared to other conduit materials, and usually lower in cost than other forms of conduit. In North American electrical practice, it is available in three different wall thicknesses, with the thin-wall variety only suitable for embedded use in concrete, and heavier grades suitable for direct burial and exposed work. The various fittings made for metal conduit are also made for PVC. The plastic material resists moisture and many corrosive substances, but since the tubing is non-conductive an extra bonding (grounding) conductor must be pulled into each conduit. PVC conduit may be heated and bent in the field. Joints to fittings are made with slip-on solvent-welded connections,which set up rapidly after assembly and attain full strength in about one day. Since slip-fit sections do not need to be rotated during assembly, the special union fittings used with threaded conduit (Ericson) are not required. Since PVC conduit has a higher thermal coefficient of expansion than other types, it must be mounted so as to allow for expansion and contraction of each run. Care should be taken when installing PVC underground in multiple or parallel run configurations due to mutual heating effect of cable

Quote:

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Originally Posted by smearcase

Since PVC conduit has a higher thermal coefficient of expansion

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That might be a consideration, but I don't know, could pull joint apart.

Golden Rule

"He who has the gold, makes th rules"

Who's got the gold, you or the contractor?

Schedule 40, sch 80 or 120. I am not familiar with a schedule 10, don't think it exists. In any case I would lay the pipe beneath the cement in gravel. There is one thing we know for sure about concrete, it will crack, always. Cracking concrete puts stress on a pipe and PVC will flex but not much, also a connection can fail. PVC will actually expand and contract due to thermal changes when the water is flowing, concrete will not expand as much as PVC. I know of no such chemical reaction with concrete but still would not do this installation. It makes me question your contractor's skill in general. I'd get 3 bids for the job, bet the other two will agree with you and me.

I agree with BallengerB1. Expansion is the major concern. One thing that helps you is by using thin wall PVC sdr21, or sdr26, (whichever you're calling schedule 10), is that it will expand and contract much easier than thicker pipes. But, the fittings will not.

It seems that you should error on the side of caution. If you are able to bury it under the concrete, that would be caution. Otherwise, you can sleeve it as I mentioned earlier. If it is small pipe, you may be able to use insulating foam which we would be real easy to sleeve. Or, as previously mentioned you could use sheet rubber. Another option is to use a little larger diameter thin-wall pipe to sleeve it.

Maybe we'll hear from Tom or Arlo. They're licensed plumbers. I'm sure they have an opinion. You may have to post the same question in plumbing to get their advice.
Al

http://answers.yahoo.com/question/index?qid=20100226083207AA2hxKh

I found this useful

http://answers.yahoo.com/question/index?qid=20100226083207AA2hxKh

I found this useful

PVC does not react chemically with concrete, Cheers, Tom

Stay away from Schedule 10 PVC - and I would suggest not to bury it in concrete. For PVC plumbing, use Schedule 40.

Milo,
My bad! I should have checked the date. We're responding to a year old thread. Regards, Tom