Pipe Allowed to Run Under NFPA 13R Building?

2/6/2019

NFPA 13 has clear requirements which do not encourage pipe to be routed underneath buildings (NFPA 13 2016 Section 10.4.3 / 2019 Section 6.4.3).

As best I can tell NFPA 13R does not have similar provisions, although the reasoning for not routing underneath is the same (pipe can become compromised by building settling, leakage is extremely difficult to repair, leakage could cause significant building damage).

Do I have any justification to not allow pipe to be run underneath a building designed under NFPA 13R? The project at hand is an attached block of apartments that has a breezeway in-between, and the contractor is looking to run pipe back underground (below footings and the breezeway sidewalk) to serve the block of apartments on the opposite side.

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6 Comments

Mike Patti link

2/6/2019 10:51:28 am

Would you not want to consider that part of the installation as underground fire main, complete with inspection for depth-of bury, size of main, etc.?

I would believe that is two completely different requirements.

PETE

2/6/2019 10:52:24 am

NFPA 24 (2016) 10.4.3.1.2 piping shall be installed minimum of 12 in. below building foundations or footers.

I don't think installing beneath a breezeway sidewalk qualifies as beneath a building.

WES

2/6/2019 10:58:28 am

I don't think the breezeway sidewalk is the issue though.

In order to go from one block of housing to the other, interior pipe on the first block of apartments would need to go from aboveground to below grade, under a building footing, underneath the breezeway (sidewalk), under another building footing, and then stub up into the other block of housing.

What difference would this be from running underneath a building? I would see the risk of damage to the pipe and the potential damage to the building from leakage as the same scenario as simply running pipe underneath a building.

PETE

2/6/2019 03:14:41 pm

Wes,
We run beneath the footing into the building all the time for a lead-in. Similarly, we run out of the building in the same manner when running to a free-standing FDC.

A leak beneath a footing can be detected and excavated from the exterior. A leak beneath a building would have to have the foundation demo'd and excavated, and would likely not be detected. 10.4.3 allows for 10 feet inside the building footprint. If it is really a concern for some reason not mentioned, consider using AMES in-building risers, which don't have any joints at the 90s.

WES

2/6/2019 03:35:22 pm

Thanks so much Pete.

Right - running under a single footing for a lead-in is done all the time, and out of necessity.

My alternative was to find a way to accomplish the same thing (connect the different apartment units) in an aboveground fashion. This could be a heated soffit or a heated pathway below a deck, in the attic space or something creative.

As currently proposed, the system would be running through more than 10 feet of interior floor slab and multiple footings on each block of housing units. To me that seems against the intent of NFPA 24 (& NFPA 13), but to your point if it only goes underneath one footing on each side and a breezeway sidewalk, then there would be limited exposure underneath the "building".

Appreciate the input Pete!

Leroy

2/6/2019 09:49:11 pm

Very frequently we run into contractors that don't want to opt for the creative options. We usually end up running copper from an interior wall under the breezeway and back up inside the adjacent unit. This "loop" is detailed in the submittals and submitted to the AHJ. In our area the FM usually elects to witness a 200 psi test on the loop before the slab is poured.

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