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Discussion Starter · #1 ·
I've always used copper to exit the building to feed the irrigation manifold. Then transition to a PVC manifold; after the valves with poly pipe. That's the way I was taught and just accepted "that's the way to do it".

I was asked recently why PVC was not used to feed the manifold from within the building to outside. Only PVC I use is for the manifold. Honestly, I do not recall if it is a "code rule" or just a "best practice". And I just figured PVC is not UV resistant nor for very long.

Then again, I've also seen irrigation in Florida where it is all PVC pipe (maybe it is different plastics?) and some of it is above ground.

Is there UV resistant PVC or other type plastic pipe used for irrigation?

How long will "regular" PVC last while above ground in sunlight?
 

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Out here, any above ground PVC under constant pressure is required to be wrapped.

That said, I have seen way too many AVB installs where the pipe is not protected in any fashion, however is still functional 15 years or more after install. The biggest problem I see with exposed PVC is it makes the pipe very brittle. Also the thinner the wall, the faster it will degrade, which is a very good reason to use SCH80 in this type of application, wrapped or not.
 

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Since no one else has stated the obvious... let me be the first...

The question "How long til degradation" can not be answered practically because there are too many variables. Just to name a few:

1. Daily duration to direct sun light.
2. The average pressure in the pipe.
3. The typical weather conditions.
4. How the pipe was treated before instillation.
5. The average number of times per month the pipe gets wacked by a weed-eater.

etc.

Obviously the 1st time #5 happens, the pipe might instantly be a gonner. Otherwise, I could see where in the worst of conditions (high water pressure, water hammer, direct sunlight during most the day) the pipe bursting in less than a year. But I could also see Sch40 surviving for over 15 years under favorable conditions.
 

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Discussion Starter · #9 ·
HooKoo

Thanks for those answers. I concur on all points.

I am curious if it is code that PVC is not allowed to feed a manifold above ground and thru the building (foundation or sillplate band joist area?
 

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HooKoo

Thanks for those answers. I concur on all points.

I am curious if it is code that PVC is not allowed to feed a manifold above ground and thru the building (foundation or sillplate band joist area?
According to http://www.irrigationtutorials.com/instal07.htm, the Uniform Plumbing Code only allows PVC plastic pipe to be used on pressure lines if it is at least 18" deep (anything less than 18" must be metal).
 

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That is for PVC, yes?
I assume that is for anything that is approved for water supply and distribution. PVC is approved for supply, but not for distribution (IRC and UPC). CPVC is approved for both supply and distribution (IRC and UPC).

FYI, my version of code check was printed in 2000.

Note, there are addition items that need to be addressed in your hypothetical situation, including state/local restrictions.
 

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In this state, irrigation supply lines do not fall under the UPC other than back flow prevention devices must be installed by a licensed plumber. It's unfortunate too because many irrigation lines are installed only 6-7 inches below the surface.

Of course any potable water lines or sewer lines are.

nearly every system I've seen uses PVC everywhere. you'll rarely see copper run anywhere in an irrigation system. But, that said even in this climate it's rare to see a pipe that's broken from anything other than being hit or run over by a heavy truck etc.
 
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