Connect Offices to Nearby ESFR System Main?

7/22/2026

There's an existing system in a warehouse with a pump. It's a grid system with an 8" main and 1" 17k ESFR sprinklers.

The main is in a 3' wide inaccessible "hallway". They added office space that will require 15 heads. There's a 4" floater main nearby.

Can I connect to the 4" main to feed the added sprinklers? What do I need to consider in doing so?

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5 Comments

Dan Wilder

7/22/2026 06:56:18 am

Other than likely having to perform calcs, existing system survey, associated water supply and fire pump annual performance test, to prove your pipe sizing for the expansion (unless there is already an existing, more remote precedent for sizing), there shouldn't be much out of the norm to complete the work on the design.

Pending the existing system layout, you may just be able to perform a TI with 1" drops from existing branch lines and avoid the above.

Glenn Berger

7/22/2026 08:14:07 am

Yes you can connect to the existing 4 inch pipe to serve additional sprinklers.

In addition to Dan's response - You do need to know how much area is being served by the current and proposed sprinkler system. There are limitations to size of the sprinkler systems per NFPA 13.

Jesse

7/22/2026 08:33:35 am

I''d make sure first that you aren't exceeding system size limitations. If not, I'd proceed with designing and calcing the addition.

Jack G

7/22/2026 11:31:50 am

Single risers are limited to 52 k sq feet.
Storage areas 40 k.
In this situation the office area must be of fire rated 2 hour construction or the office area is classified as the same Hansard as the rest of the space. Walls maybe with a mezz. Or just walls with a ceiling. Temperatures of the sprinklers should be coordinated so that the roof and ceiling areas do not operate at the same time.
I d have to look this up but I ve had AHJ s ( if ceiling and grid are rated for 2 hours ) allow clips to hold the tiles in place to separate the 2 classifications and system occupancies .

Pete H

7/23/2026 08:16:27 am

You can do it.

It's a longer calc. but if it calcs, you can do it.

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Connect Offices to Nearby ESFR System Main?

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