Where is C900 Allowed for Underground Service?

3/4/2022

When is C900 PVC allowed below buildings before the transition to metallic pipe for spigot stub up?

I often see municipal rules to keep non-metallic pipe no closer than five feet from the building foundation.

Where does this requirement come from?

I have no problem with this practice but would like some code justification to discuss this with contractors.

Thanks in advance.

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5 Comments

Jack G

3/4/2022 09:18:48 am

It depends on municipality. Some in the tri state area, Philadelphia, do not allow it.
Phillie will allow it for fire mains, after a meter pit.
So it depends.

Mike

3/4/2022 09:42:39 am

Usually DI is required because of the weight of the foundation.

Alex

3/4/2022 11:52:09 am

Hi,

Similar discuss post here: https://www.meyerfire.com/daily/is-blazemaster-permitted-underground

I would assume the municipal rules stem from the weight of the foundation, therefor, requiring DI.

I would agree with Jack that this is a municipal decision and would reach out to your AHJ for guidance.

Thanks,
Alex

Casey Milhorn

3/4/2022 03:43:44 pm

Great question. So typically your water department has the say so to the backflow preventer and/or to the property line. In the South we see a lot of water departments specifying only cement lined DI (Class 50, 52, 350, etc). But some do allow C900 before the backflow as well. After that point it is typically up to building codes/fire marshal and most of the time it is acceptable. So check your specs (if you are the sprinkler designer), check water dept, and check codes/fire marshal.
Also, be aware of the pressure ratings of the different classes of C900. Dr18 used to be only good up to 135 psi I believe, but now is good to 225 I believe. Dr14 was around 235 psi but good up to 315 now I think? Verify that. So in most instances Dr14 or Dr18 is plenty, even when used for FDC supply mains (in most cases). I have never seen Dr21 or higher used for sprinkler, nor do I think it is listed for that.
Also, I do believe NFPA 24 has some verbiage about acidic soil concerns when using PVC type pipe. Some testing and/or protection measures may be required. Check your applicable edition of 24.

Cesar Flores

3/4/2022 07:22:01 pm

I agree with Casey. Per NFPA 24 you can use C900 exposed to build longest it restraint. But there is certain restrictions in some areas.

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Where is C900 Allowed for Underground Service?

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