1-in Outlets OK for Shell if Tenant May Use K16.8?

7/21/2025

Sprinkler is being installed in a warehouse as part of a "base building" phase.

There are 1-inch outlets being proposed as the outlets on branch pipe, but a potential tenant is requesting a system that may require K16.8 ESFRs.

Are tenant fit-out sprinklers permitted to be installed over bushings in this situation, by code?

There will be a 5-year tenant lease, but no guarantee of resigning or extension on the tenant.

Thanks in advance.

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9 Comments

Pete H

7/21/2025 06:22:06 am

Why would this need a bushing? Most 16.8k heads are 3/4".

There are 1" x 3/4" reducer couplings the sprinkler can attach to. Are these 1" female outlets? Can you add a shoulder nipple and then a reducer coupling?

There's not enough information as to whether changing the heads without relocation/additional heads will result in a code compliant system, I'd personally doubt it given the difference in K factors. But if it calculates and you use listed materials, you can have 16.8K Sprinklers off 1" outlets in a tenant build-out.

Jesse

7/21/2025 08:12:51 am

In remodeling a shall system for a finish-out, my standing order is to always match the existing K-factor or calculate the system changes. Most K=16.8 sprinklers are 3/4" and some are 1".

Shouldn't be an issue if the shell system uses K=16.8. If it doesn't, you'd ned to calculate anyway so I think it would be good

7/21/2025 08:13:44 am

ESFR sprinklers arent that much more expensive than standard spray sprinklers for new construction. I'd talk to the building owner about using K25 ESFR or K16.8 ESFR sprinklers for the base building to simplify/minimize future sprinkler modifications as tenants change. This is much simpler than what you're describing (which sounds like something that was requested by someone that probably doesnt understand what they're requesting) and will also help with ESFR obstruction considerations early on in building construction which will also helpful for the owner.

Chad

7/21/2025 08:48:36 am

I second this, max out the demand around water supply and dont have to change it later.

Dan Wilder

7/21/2025 08:22:20 am

13-19' Edition

16.3.12 allows for bushing to accommodate future ceilings and most building have the ability to be fit out so this shouldn't be an issue. NFPA just doesn't want reducing fittings using bushings if the more standard threaded reducing coupling is available.

I would make sure the system can handle an ESFR hydraulic demand as well. Just providing outlets without verifying the system capabilities is doing a disservice to the owner as to expectations.

Glenn Berger

7/21/2025 08:35:21 am

NFPA 13 - The 2025 version revamp the clarity of utilizing bushings from the 2022 version (which had been in the standard for a significant period of time). In the 2025 version see Section 30.5.2.1.

Ricardo Gonzales Jr

7/21/2025 09:01:57 am

I would recommend doing a sample diagram and see what the system calculates out as. You'd spend more time to justify the smaller pipe than to do a sample system. Then you'd have backup for your decision.

danefre

7/21/2025 09:06:13 am

Careful with this as it's a pretty common request from owners that don't understand the ESFR requirements.

Unless the entire system is designed with consideration to structural elements, MEPs, ESFR spacing etc, it's a moot point trying to design for "future" ESFR. Can you prove that the system will work for the maximum storage height?

The outlets is the least of your problems. Typically, in an ESFR retrofit (that's what this will be) all the branchlines will be replaced.

I would design the actual base building system for ESFR assuming all the other requirements are met.

To answer your question, you will get the most flexibility by designing 1" IGS outlets which will work with K16.8 IGS and K25.2 IGS. The heads come with reducing couplings.

Jack G

7/21/2025 12:26:24 pm

Personally I feel that using a large k factor sprinkler in a tenant space or combo warehouse tenants fit out is a no no.
If the calculations are for “ warehouse design”, when you go to do the cut up tenant space, you will not have enough water.
Most buildings like this specify to be able to take 2 sprinklers off each outlet— this gives the owner a cheap design without having to replace lines and mains later.
Some specs tell the tenant that chasing piping if their layout exceeds the system demand that it is on them.

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1-in Outlets OK for Shell if Tenant May Use K16.8?

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