Required size of a watermain for a single family home

[msm15]

Hi I am in NYC, we are building a few single family homes. Our Architect is calling for a 3" combined line for SP and DOM service. The houses are detached - 24'x54' with 3 floors with a total of 34 heads. we brought in a street plumbing for pricing on the street mains and he is telling us we don't need a 3", and he does these on 2" all the time - but he's not an Engineer said we should recheck with the Engineer.

When I questioned the Architect he said code requires a 3" for a single family home with more then 20 heads.

I checked NFPA 13D and cant find anything stating that - is this accurate ? any direction here would be appreciated as it makes a big difference in cost.

We did a larger house a few years back but it had the same number of heads and it was on a 2" combined line so I am inclined not to believe what the architect is saying...

Thanks

 

[skdesigner]

Nothing in 13D that would require a 3" water supply. Just ask the architect for the code reference.

 

[msm15]

Yeah he doesnt know it. Just said it was on a chart...

 

[MJCronin]

On a chart, he said ? ... Perhaps one that he found under a desk somewhere ? ...

Well, that sounds totally legit to me ....

MJCronin
Sr. Process Engineer

 

[msm15]

Yeah hence my question.

 

[skdesigner]

2020 Residential Code of New York State doesn't appear to require it.

https://codes.iccsafe.org/content/N...d-distribution#NYSRC2020P1_Pt07_Ch29_SecP2904

The only chart I'm aware of that specifies 3" pipe where more than 20 sprinklers are present would be the ordinary hazard pipe schedule table in NFPA 13. Definitely doesn't apply in your situation.

 

[msm15]

Yeah, agreed but I would not be surprised at all if that was "the chart" he was referring to.

Thank you all for your info, I just needed to some backing to get a different engineer involved.

 

[cdafd]

1. Have you asked the local city or water supplier if they require3 inch?

2. What does your fire sprinkler designer say??

This is for both domestic and fire???


Are they talking the meter itself??? 3 inch?