Concealed EC Sidewall at 18" Below Ceiling?

11/25/2025

I have a contract that calls for concealed, extended coverage horizontal sidewalls in an area with a Turf Switchblade Acoustic Ceiling. The issue I'm running into is that the Tyco RFIII EC HSW has a maximum distance below the ceiling of 12", and the acoustic has a maximum dimension of 9.4" down from the ceiling.

Therefore, I won't have the 4" minimum distance between the deflector and the obstruction.

Has anyone else encountered this type of issue?

Has anyone found a concealed sidewall extended coverage that can be 18" below the ceiling?

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8 Comments

Pete H

11/25/2025 07:49:47 am

They're not concealed, but based on this thread:

https://www.meyerfire.com/daily/sidewall-sprinkler-listed-18-inches-below-ceiling

I'd say you're looking at the Tyco EC-5 Sidewall if you want an extended coverage sidewall that can be 18 inches below ceiling.

Colin B

11/25/2025 11:32:00 am

Thank you, I actually submitted those as an option with my RFI to the GC and Architect. They Specified concealed on the specs. Waiting to hear back. Thanks again.

Jesse

11/25/2025 08:18:13 am

In my humble opinion, HSW sprinklers are the most mis-used sprinklers out there. Their listings typically indicate usage beneath a smooth, level / flat ceiling or specify a slope they can be used with.

We've all seen HSW sprinklers installed beneath open canopies with exposed structural members. I highly recommend the Sprinkler Database in the Meyer Fire Toolkit. For those not using this tool, you're doing yourslef a disservice. If such a sprinkler is out there hiding, you'll find it there.

Colin B

11/25/2025 11:32:39 am

That's a great tool I was not yet aware of, Thanks!

Jack G

11/25/2025 11:04:57 am

A metal grid ceiling with tiles is usually considered a smooth ceiling per nfpa 13.
If the magnetic switch blades were 4 inches, they would be considered a small non structural non continuous obstruction and are unlikely to reclassify as obstructed for EC horizontal sidewall sprinklers.
The magnetic switch blades are not a concern unless they are within the 18 inch vertical clearance from the sprinkler deflector where they could disrupt the spray pattern or if they are large ebough to require a repositioning based on the 4 times rule for EC sprinklers. ( review your sprinkler spray pattern for the arc from deflector to ceiling)
If the switch blades are significantly higher than the deflector they would not be considered an obstruction.
Consult nfpa 13 and AHJ for placement of the sprinkler head..
In my opinion , with the information given, you may not be able to use an EC sidewall unless the upward trajectory of the sprinkler is below the switch blade and the measurement from the ceiling at the same time is 18 inches .
You should prohably reconsider the space with the architect and the AHJ.

Colin B

11/25/2025 11:33:45 am

That's exactly the point I am at. I have an RFI sent in explaining the issue and am waiting for answers, just wanted to see if anyone had experience with this issue and knew an easier work around. Thank you for your reply!

Randy Rathert

11/25/2025 12:32:02 pm

That is one of the best conversations that i have followed on this site.

Mike

11/26/2025 10:33:35 am

Just from a Google image search, these don't even look like they qualify as acceptable construction type for sidewall sprinklers.

Project specifications sound like an architectural fairy tale.

There's no way the ceiling jet would be able to go across the ceiling and then down the wall to activate the element.

That's why there are so many limitations to HSW installations.

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Concealed EC Sidewall at 18" Below Ceiling?

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