Have you had a project with an overhang that needed sprinkler protection and extended just beyond the throw of a dry sidewall sprinkler?
 
It’s a smooth, flat or nearly-flat overhang that’s, say, 21’-6” wide, and in an environment that will dip below 40 degrees F at some point.
 
What are your options then?
 
OPTIONS
All of the extended coverage dry sprinklers we know on the market cap out at 20’-0” horizontal throw. That would have been our best option.
 
We could look at using a dry system. There’s the additional cost of the valve, slope requirements, a hit on the remote area size, more corrosion potential – and on and on. It’s costly.
 
We could look at an anti-freeze system. Those come with more restrictions than they used to, but at a minimum would involve an RPZ and now pre-mixed antifreeze solution. Additional cost.
 
Heat trace the pipe? That’s problematic, at best. It needs to function 100% of the time that it’s needed, or pipe will freeze. It needs to be supervised. It needs to be maintained. And when in conjunction with pipe insulation it looks terrible.
 
In short, an overhang that’s just beyond the reach of a dry sidewall sprinkler can take us to a whole new cost tier in the design of a sprinkler system.
 
CODE-COMPLIANT CREATIVITY
We had just this situation on a project a few weeks ago, and tried to think creatively to get a code-compliant solution that’s best for the owner, yet doesn’t spike the cost for a dry sprinkler system that only serves four sprinklers.
 
Now normally, sprinkler design tends to be a one way street. An architect designs a building. It gets bid and handed down to the sprinkler contractor. The sprinkler contractor “makes it work” with what they’ve been given.
 
If a consultant is on-board, this would be a great opportunity to pick off challenges like this and advice the architect and owner on ways to mitigate this cost spike for a small project. Perhaps the overhang is designed at 19’-6” instead of 21’-6”. Perhaps they build it with all non-combustible materials if it otherwise didn’t have storage below.
 
Those could be helpful changes that reduce the overall cost in a major way, but may not be a major detriment to the owner’s goals for the building.
 
#1 SHORTEN THE OVERHANG
Regardless, we suggested that the width of the overhang be actually shortened to allow a sidewall’s throw to cover the distance and prevent the need for a whole dry system.
 
That didn’t go anywhere.
 
#2 EXTEND THE REACH OF A DRY SIDEWALL
We then asked if a soffit could be built to allow a sidewall it’s spacing of no more than 20’-0”.
 
The soffit wouldn’t have to be heated. It could simply be framed (hopefully of non-combustible studs) with sheetrock or a “Hardie Board” or some other skin. It could be almost completely empty on the inside.
 
The goal would be to give a dry sidewall sprinkler a back to collect heat and be installed properly.
 
KEY RULES
There’s a few notable rules that come into play here, though.

1. Extended coverage sidewalls need to be within 6” (150 mm) of the wall which they are mounted (Section 11.3.5.1.2.1, NFPA 13 2022 Edition).
2. If the soffit is more than 8-inches (200 mm) in width, then a sprinkler is required below the soffit (also Section 11.3.5.1.3.1, NFPA 13 2022 Edition).

 
So working backwards, a soffit that is say, 2’-0” wide and 2’-0” tall would allow a dry sidewall sprinkler to:

1. be mounted to the side of the soffit within the 6” of the ‘wall’ which it is mounted,
2. allow the height of the sidewall to be 6” from the deck above,
3. allow the dry sidewall length to be long-enough to have the dry barrel run all the way through the width of the soffit and extend into the warm heated interior space, and
4. limit the throw distance of the dry sidewall to less than it’s maximum of 20’-0”.

 
But then, we need coverage below the soffit too, right?
 
This could be accomplished with a flexible dry pendent, such as the V3517 dry flexible pendent sprinkler. Just like the dry sidewall, the flexible dry pendent could contain water back on the warm interior space.

DIGGING DEEPER
We also would want to offset these locations on plan, so a pendent isn’t immediately under a dry sidewall. Offsetting the locations in plan could help potential cold-soldering concerns.
 
We’d also want to be sure that both the dry sidewall and the dry flex pendent would be able to be replaced at some point in the near future. NFPA 25 used to require sample testing or replacement every 10 years starting at 10 years after installation, but the 2020 edition bumped that starting point up to 15 years and the 2023 Edition bumped it again to 20 years after installation (NFPA 25 2017-20 Section 5.3.1.1.1.6, 2023 Section 5.3.1.1.1.5).
 
To accommodate replacement and testing, we might need a way to get access to the inside and the soffit in the future (access panels or future cutout).
 
COST & CONSEQUENCE
After all this effort – will the soffit cost more? Sure.
 
Would it cost as much as a dry or anti-freeze system? No, it shouldn’t.
 
Does it help with corrosion and IT&M in the future, considering we wouldn’t have a dry valve and an additional nitrogen system or air compressor? Yes, that’d help too.
 
Just an idea that might help address those “in-between” situations that could spike cost for a smaller-sized project that otherwise wouldn’t need it.

What are your thoughts? Have you tried this before? What tips would you suggest?
 
Hope you’ve found this interesting and perhaps moderately helpful, and I hope you have a great rest of your week!

We tried out something new a couple months ago with a Detail Pick-Apart covering a dry sidewall sprinkler at a deck. We had a great response - healthy discussion from a wide variety of perspectives.

Way back when we even talked about different parts and purposes for components of a wet riser. 

It's the dialogue that I often find the most helpful in seeing and understanding perspective that I simply just don't have.

No detail is perfect, nor is it applicable in all situations. No way. It's one possible solution to some situations.

That said, it can be really helpful to have open discord and learn from it. 

Quick rehash on ideas for critique and discord:

USE CASES: What are good use cases for this? 
PROS: What benefits does an approach like this bring?
CONS: What are the negatives with an approach like this?
IMPROVE: What ways can this approach be improved?

What critique would you offer here?

Thanks, as always, for being part of making the industry better.

I'm going to go out on a limb here and do something I'm a bit apprehensive about as an engineer.

#1 FLAWS IN THE ARMOR
First - my number one fear of writing when I first started was that I was going to be wrong, and I was going to expose it for the world to see. 

After all - Engineers are never allowed to be wrong. And when we are, we're not allowed to openly admit it, right!? Anyone? 

Ok now that I've offended my friends, I should say that I'm flawed. I don't mean that facetiously. I've mostly gotten over the fact that I don't know everything; I have gaps in my knowledge. And even the things I do feel pretty adamant about, I'm still learning ways in which even those areas need improvement. I'm learning all the time.

So acknowledging first that I am flawed and make mistakes is piece number one.

#2 OPEN DISCORD
Second - it's better for the world to bring discussions out into the open - where we can all learn from it.

That's the entire point of the Forum, the point of writing as part of this blog, the point of MeyerFire altogether. What conversations can we start that everyone benefits from?

In that line of logic, today I'm posting this detail that is a sketch I put together for open critique. Hopefully, if this is something we all learn a little from and gain some useful knowledge, maybe it's something we can do again with different situations.

#3 IDEAS FOR CRITIQUE
Before we fire away, remember that any detail is simply an approach, a concept. It's one possible solution. It's not a cure-all for every situation. It's simply one approach of many.

I'd like to propose a few prompts to help the discussion related to this specific approach:
​
USE CASES: What are good use cases for this? 
PROS: What benefits does an approach like this bring?
CONS: What are the negatives with an approach like this?
IMPROVE: What ways can this approach be improved?

Here's the concept:

So - what critique would you offer here?

What are good and bad use cases? Pros and cons with the approach? How could it be improved?

Thanks, as always, for being a part of making the industry better.