I'll start by saying I'm not perfect. I've learned some things the hard way that I could have avoided, which in part spurned this whole blog. This week's topic covers one of those things learned by trial and error (but mostly error).
If you are responsible for fire protection bid plans and you expect a contractor to provide hydraulic calculations, then you should include flow test information on your plans.
"If you are responsible for fire protection bid plans and you expect a contractor to provide hydraulic calculations, then your plans should include flow test information."
NFPA 13 does just about everything but require a flow test to be completed on the preliminary plans.
Annex material, for instance, has long spelled out that preliminary plans should be submitted to the AHJ prior to the development of working plans by a contractor (A.14.1 in 2002 Edition, A.22.1 in 2007-10, A.23.1 in 2013-16, A.27.1 in 2019). These preliminary plans should include test information with date and time, conducting party, location of hydrants, and size of mains.
Water supply information is a critical part of the overall fire protection equation but it's value comes before bidding as well as after.
If it is not a requirement in 13 to have it included in preliminary plans, then why provide it when the contractor can?
Well, there are several reasons.
1. Determine Fire Pump & Water Storage Tank Prior to Bidding
Is a fire pump required for the project?
It’s an important question – the cost impact to an owner is often between $50,000 and $120,000 between the pump, controls, piping and equipment, and possible generator when a pump is required.
The only thing more expensive than a fire pump or water storage tank included on a project
is when they get added as a change order.
Is the available flow to the site low, needing a break-tank or a full water storage tank?
The cost impact to an owner here is even greater.
If a flow test is not included on preliminary plans, how is a contractor supposed to confirm that a pump or a tank are not necessary? Take the word of the engineer? Guess based on past-history?
For flat-terrain areas with little construction activity over time, anticipating the available supply might be possible. For hilly areas where I live with a wide variety of water main sizes, it can be next-to-impossible to guess an available water supply at any given location.
If you are a prudent contractor and you are to bid a job without clear water supply information, what would you do? Bid a price conservatively high to anticipate large pipe sizes with a poor water supply? That’s possible – but then you’re also far less likely to win the job. Bid a competitive price, but exclude larger pipe sizes or a fire pump/tank? That could work to win the job, but what happens when the actual flow test is run and you determine a fire pump is necessary?
I’ll tell you what happens – the owner gets a very large change order they weren’t anticipating and the general contractor, sprinkler contractor, and design team all look bad.
Part of my role is creating upfront preliminary plans for owners & architects that go out to bid, but I also work for sprinkler contractors to produce installation/shop drawings. I’m very fortunate in that I get to see both sides of the industry.
A Real-World Example
One current job that I’m working for a local sprinkler contractor on is a new-construction five-story medical office building. It’s a great building with tall floor-to-ceiling heights and a fifth-story ceiling that’s about 80 feet above ground level.
The preliminary plans call for an FM Global Hazard Category-2 shelled area (0.20 gpm over 2,500 sqft) on the top level. Once the flow test came in, even with good pressure, it wasn’t enough to support this hazard classification.
Could the hazard classification get bumped down to better align with the future tenant use? Possibly. Could a fire pump be added to the project at a significant cost, late in construction? Possibly.
Either case, this all could have been avoided had flow test information been provided on the original plans. Bidding contractors wouldn’t be eligible to claim large change orders based on unanticipated pressure, and they can flag issues before they even submit bids.
2. Reduce Potential for Major Change Orders
Too often the single cost that a building owner is concerned with is the total cost of the job at bid. They should be concerned about the total cost of the project, including change orders and including the lifecycle of the system.
What good does accepting a low bid do if it is later rife with change order cost additions? It happens all the time with poorly prepared bid plans.
Including a flow test as part of the preliminary plans removes a major potential change order opportunity as it enables the sprinkler contractor to do their own pre-bid layout and calculation should they choose to do so.
3. Removes Potential Conflict of Interest
I have encountered misreadings of pressures from a gauge in the field, test results that were incorrectly copied between documents, and flow tests that were suspicious enough to go and re-test.
I (thankfully) have never come across anyone doctoring flow test numbers.
Is it possible that a contractor could fudge flow test numbers to save on pipe sizes and improve their bottom line? It’s possible. Virtually all of the contractors I’ve come across are very proud of their installations and are in the business because they care about life safety. Have I ever seen it happen? No. Could it? Yes.
When an engineer provides the water supply information upfront, however, this potential conflict of interest evaporates.
Including flow test data (or fire pump/water storage tank information) can be a critical piece
for bidders to properly assess and bid a system.
4. It’s Not That Hard to Get
For all the information we expect contractors to produce after they win a job, could we as engineers not produce such an important (and basic) piece of information?
Some water purveyors run hydrant flow tests at no cost. Some jurisdictions will do the same.
Even when both don’t run the tests, you can do it yourself. Read and follow NFPA 291, watch some videos, pickup a flow test kit for $400-$600, and remember to open and close valves slowly. It’s not terribly hard to do.
If you aren’t interested in running the test, hire a contractor. I’ve seen tests run as cheap as $150 and as expensive as $1,200 (a 3-hour drive each way), but they are often between $350 and $550 to have completed. Local contractors are more than capable of providing this service and they can do so quickly.
One of the biggest hassles in running a test early is often the tight design schedule many projects are on, and explaining to the owner why a flow test should be done upfront when a sprinkler contractor could just to it later. This article at least helps you address the later concern.
5. It’s Fair to Bidders
Bidding contractors are often not as concerned about how much or how little you want them to do. If you want schedule 40 throughout, they’ll provide schedule 40 throughout. If you want a nitrogen system, they’re provide a nitrogen system.
What contractors are extremely concerned about is that their bid price is fairly compared to other contractors. They will not provide schedule 40 if they feel another contractor will not provide it. Same with nitrogen or any other upgrades that could otherwise greatly benefit the building owner.
Water supply information is one of those key pieces of information that allow contractors to bid on an even playing field.
6. Retain Data History
How often do you find old building design documents that don’t include shop drawings? If you’re like me, it’s all the time. An engineer’s pre-bid plans don’t often have a wealth of helpful information – but having a little water supply block is a helpful data point when comparing historical water supply points.
Since engineer’s preliminary plans often get stored and tracked with the rest of the construction documents, including the water supply information can be a helpful way to retain that information for designs and renovations in the future.
I’ll slowly now descend from my soapbox by saying again that I’m not perfect. I’ve sent far too projects out to bid without water supply information than I would like to admit, often without any legitimate excuse. As an in-house goal we now try to hunt down water supply information for every project that we expect to see a hydraulic calculation by the contractor. That’s every building addition, occupancy hazard change, and every new construction project. It’s just too important of a data point to leave out for bidders.
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I'm excited to announce a new addition to the Toolkit that has been in development for a long time - the NFPA 13 Edition Translator.
With the major restructuring changes in the 2019 Edition of NFPA 13 - it has been difficult for me to flip straight to the content I'm used to doing. From the feedback I've heard I'm not alone on that learning curve.
As a result, a couple weeks ago I released the first version of the translator, which takes any numerical section from the 2016 or 2019 edition, and returns the matching section from the opposite edition.
Full Tool Now Available
This full version is quite the powerhouse. With over 130 hours of research included, it can now take any numerical section from any edition of NFPA 13 from 1999 through the 2019 edition, and returns the matching section throughout it's history.
A quick search on the edition translator shows the history of the section and where it appears.
Why could this be helpful? If you work across multiple jurisdictions or your local jurisdiction just updated to a new edition of NFPA 13, the shift in organization can be frustrating.
If you use the free versions of NFPA 13 that are supported by NFPA, then this tool could help you quickly navigate equivalent sections.
Probably the most common use I have is finding the back-history of where a section first appeared and where to look for it in past editions. This comes up occasionally for projects when there's disagreement about a particular section of code and searching for the back-history and any clarifications in future editions is very helpful.
If you're a Toolkit subscriber, you can download the latest version of the Toolkit, including this edition translator, here.
I've made it easier to download updates for Toolkit users. You can access the latest version and quickly download it at www.meyerfire.com/download. No sign in required.
Find this interesting? Consider sending to a friend or colleague who might find it helpful.
Following the interest and popularity of the ceiling-mounted obstructions tool, I've been working on some new tools that cover other obstruction situations which we often encounter. This week's post is a quick demo of the progress for one of these obstruction situations, which is the soffit against a wall condition.
One way NFPA 13 addresses soffits is by shifting a sprinkler away from the wall, which allows water from the sprinkler to throw below the soffit. With only two input values this tool will quickly determine the horizontal distance a sprinkler needs to be located away from a soffit in order to meet NFPA 13 Figure 126.96.36.199.2(b) (2016 Edition).
Give this demo tool a quick try and comment below with any concepts you'd like to see added to this tool or the site. Thanks in advance!
When I was six years old, I came home from school unexpectedly excited one day.
I ran up our driveway, pushed wide the door and yelled to my mom.
“You won’t believe it! There’s this place at school where you can go through shelves and shelves of books and pick out anyone you want –
and it’s free! They call it a library.”
It wasn’t one of my mom’s proudest parenting moments, but in our house, we never pretended to be great readers… or apparently even pretended to introduce kids to a library.
I guess I’ll just come out and say it… Both of my parents are accountants.
Now, I know what you’re thinking, and yes, the accountants are where my well-rounded sense of humor comes from.
But there’s another big benefit to having parents as accountants –
and it’s having a love for spreadsheets.
I’m not sure if little excel formulas naturally run through my veins or whether it was every family calendar my parents ever created, but one way or another I thoroughly appreciate the power a spreadsheet has.
Even if your parents are not both CPAs, there’s a place for Microsoft Excel in your engineering life.
Excel isn't just made for your uncle accountant anymore - there's potential any engineer can love.
For one, Microsoft Excel is not called
the “Swiss Army Knife of Software” for naught. Excel is a blank canvas for any calculation you need to make. You can quickly create and repeat repetitive calculations to speed up and organize your workflow. You can complete reports, forms, create charts, tables, organize content, or use any of a myriad of highly powerful tools.
Here are a few of my most often used formulas:
That’s pretty much all of my secret sauce. About 95% of the tools created combine those formulas alongside mathematical operators (like max(), min(), sin(), sqrt(), etc.).
One of the best parts about using Excel is that you may already have access to it. If your company has a Microsoft Office suite (or what’s now their subscription model with Office 365), you already have access to these tools.
Creating helpful resources is what we’re all about, and Excel is the epitome of giving you, the rockstar designer or engineer, the ability to create and flourish with the tools you need.
You didn’t get into the industry to do poor, sloppy work. You came here to help save lives. We shouldn’t have to wait for programmers to create the daily tools we need to do great work. Excel is one way you can organize and validate the great work you do.
There came a point near the end of my undergraduate work and at the beginning of graduate school where I realized I needed to create a clean, organized method to show details within calculations. The method I slowly developed needed a single logic path, had to be easy to follow, would thoroughly explain the process, and had to allow the easy repetition of the work.
What’s resulted is the standard format that’s used in the PE Prep Guide and on many of the tools you’ll see around this site. Concepts are researched, painstakingly created, tested, refined, tested, refined, beta tested, and refined more.
Standard formatting for MeyerFire tools - note the equations and worked examples with references cited.
If you’ve followed the blog for a while, you already know the blog, daily forum, and even the PE prep materials are all created to help foster discussion that leads to shared expertise and knowledge.
Outside of a few major players and organizations, the fire protection industry is comprised of thousands of thousands of small outfits that welcome this shared expertise. Our industry thrives on the contributions from a wide spread of individual parties.
Don’t let me or anyone else douse your enthusiasm to create resources that improve your ability to impact the industry.
Keep on keepin’ on.
Oh and remember to take your kids to the library.
Looking for an opportunity to turn a basic concept into a controversial one on a project? Great! This week I'm exploring the quick-response remote area reduction that's provided in NFPA 13.
Suppress Early, Suppress Less
The concept behind reducing the calculated hydraulically remote area in a fire sprinkler system is entirely based on fighting a smaller fire earlier in the development of the fire.
There's a handful of factors that contribute to the timing of sprinkler response (a good future discussion), which include the thermal sensitivity, sprinkler temperature rating, distance of sprinklers relative to the ceiling, sprinkler spacing, ceiling height, and dynamics of the fire itself.
The reduction in the hydraulically remote area is based upon comparative tests of quick-response against standard-response spray sprinklers. According to the NFPA 13 handbook, the tests demonstrated that the earlier the water is applied to the fire, the smaller the fire and ultimately the less number of sprinklers needed to activate.
Not Universally Accepted
While the remote area reduction has been included in NFPA 13 for years, it's not universally accepted. Many engineer specifications don't allow the reduction, and design standards for major organizations such as the Department of Defense (UFC 3-600-01) don't permit it either.
Why not accept the remote area reduction, if NFPA 13 includes it? Like other elements in hydraulic design for fire sprinkler systems, not using the remote area reduction provides an additional safety factor to the system.
Additionally, since the quantity of sprinklers relates to the quantity of water flowing in the system, main sizes are directly impacted by using or not using the quick response area reduction. Building owners may opt to not want to reduce the remote area to preserve reasonable (larger) main sizes and give themselves flexibility on building modifications and sprinkler system changes in the future.
Quick-Response Area Reduction Calculator
This quick calculator is in part a checklist of prerequisites to reduce the remote area on a fire sprinkler system, in part a method of showing your work, and in part a quick calculator on determining your final remote area size. Don't see it below? Give it a try here.
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When I first started in the industry I worked on a long line of high-end retail projects scattered across the United States. Six months after starting I got a question from a project manager about concealed space wood-structure sprinkler protection on a particular store in San Jose.
San Jose? I was positive I never worked on a project in San Jose.
A little digging later revealed I did in fact work on a small retail shop in San Jose. The only problem was that it looked just like the other 30 stores I had worked on in-between. Did I evaluate protection or even consider the combustible above-ceiling space? Did I discuss anything with the AHJ?
I quickly realized that if I didn't take project-specific design notes I'd have no way of revisiting my thought process when a question inevitably arose later in the project.
The Mad Man
Ever since then, and not entirely due to my undiagnosed organization issues, I've been on a mad hunt to find the best way to record project notes in the cleanest and most insanely-quick process possible.
For me it's partially about recording the design thought process, and partially about reminding myself about all the considerations that need to occur for a project.
I can't say I've tried every method for project note taking, but I have used word templates, checklists, spreadsheets, OneNote files, linked databases, access databases, and the good old pen and paper.
I have several goals when devising project notes for me and the staff I work with:
An example project design sheet (click to see full PDF)
Here's where I am now - an excel-based, single page note page where a quick "X" above a cell highlights the one below. If I know all of the information in a project, it can be filled out completely in less than 3 minutes.
It can be a helpful accompaniment for sprinkler contractor clients when we're submitting a bid, or helpful notes to accompany a QC set of drawings.
What Am I Missing?
I'm sure your checklists and cheatsheets include a wide variety of considerations. In my attempt to better this one and incorporate the whole spreadsheet, what important elements am I missing? View PDFs below, and post your comments & feedback about important things to add here.
Find these conversations interesting? Forward to a friend or subscribe to these weekly posts here.
If you've been following the blog for awhile, you might already know about the Toolkit that has really taken off lately. This past week I've incorporated some (great) user feedback and now have a new version to present:
I've revamped the organization and it's FAR easier to navigate and use now.
With a new main menu and crisp pages the Toolkit is FAR easier to navigate. Now you can get what you need, quickly.
If you're already a subscriber to the Toolkit, use the download link below to get the latest version right now. No need for any new access codes - it just updates the Toolkit right over your current version.
A clip of the latest version of the Sprinkler Obstruction Calculator on the MeyerFire Toolkit.
What is the Toolkit, and what does it include?
The MeyerFire Toolkit is a downloadable series of excel-based tools that allow fire protection designers, engineers and code authorities to quickly calculate a myriad of regular applications. With this tool you can save time with quick but powerful tools that you can save, PDF, or print.
The Toolkit contains all of the tools you see on this website - plus the popular Fire Sprinkler Database - which is a live collection of all fire sprinklers on the market where you can sort and filter to see what products exist for your application, and then specify or design the ones that best match your design goals.
A Free 30-Day Trial, Starting Today
If you've never seen the Toolkit, or have used a trial version before and are interested in testing the new look, download the toolkit with a trial code (good through late March) here:
There's a few new additions to the Toolkit I hope to debut in the next couple weeks based on suggestions from users just like you. If you're an expert in fire flow calculations or water storage tank design and are interested in early testing, email me at email@example.com.
If you know someone who might be interested in giving the Toolkit a try, email them about downloading it today. As always, you can subscribe to these weekly articles & resources here.
First - thank you for such a warm response to last week's article on a major and thorny topic of using sprinklers alongside glazing in rated assemblies. I genuinely appreciate and am motivated by so many thoughtful people in our industry.
As I mentioned last week, below is a link to the original article with the new PDF summary. It compares rated window assemblies, use of closely-spaced sprinklers for atrium enclosures, and the use of window sprinklers across many important categories.
If you find this useful, please consider sharing with others who also may be interested in the content. If you're not already subscribed, you can get this and many other similar resources for fire protection design, inspection, review, & engineering by subscribing, for free, here.
Thanks & have a great weekend!
Perhaps one of the most seemingly straightforward but actually complex topics of fire protection is the use of fire sprinklers to achieve passive fire resistance requirements. This week I'm diving into an introduction of different methods of using sprinklers for passive fire protection and discussing some of the design abuse therein.
If you've encountered it, you're surely already familiar with how big of a topic it is.
Three Methods for Protection of Windows
Where windows are provided in fire-resistance rated components (a fire partition or barrier, as sprinklers are not permitted to be used for fire walls), the opening must be addressed in a manner that maintains the fire-resistance of the rated enclosure. The driver for these requirements is the building code.
Option 1: Rated Glazing
The first method to address openings in rated walls is provide a glazing assembly that is rated.
The International Building Code qualifies two types or ratings- fire-resistance-rated or fire protection rating. The former is tested to ASTM E119 or UL 263 and is not considered an opening. The later (fire protection rating) is tested to NFPA 257 or UL 9 and has limitations on overall size. (IBC 2018 Fire-Rated Glazing Definition)
Of the three options, this one is the most costly. Cited costs of fire rated glazing alone can be nearly $100 per square foot. For a large 10 foot x 6 foot window, for instance, that's over $6,000 for each panel.
Option 2: Closely-Spaced Sprinklers (for Atrium Enclosures)
Closely-spaced, standard sprinklers are used in glazing applications specifically for the protection of an atrium enclosure which contains glass.
The closely-spaced sprinklers, used in conjunction with specific requirements for glass and frame, are only permitted in the International Building Code as an alternative to a 1-hour enclosure for atrium spaces. (IBC 2018 404.6)
I'll discuss this in more detail, but the big takeaway here is that the building code only permits the use of closely spaced sprinklers as an alternative to a 1-hour enclosure for atrium enclosures.
Closely Spaced Sprinklers used in lieu of a 1-hour wall for atrium enclosures are the least-restrictive setup for sprinklers and glazing, with limited dimensional requirements and allowed use of multiple standard sprinkler types.
Option 3: Window-Style Sprinklers
The last method for treatment of windows in fire rated assemblies is to provide Tyco Window-Style sprinklers installed in accordance with their listing.
The proper use of these sprinklers can achieve up to a 2-hour fire resistance rating with the use of glass. This method is not a prescribed code application but rather an “alternative method of construction” which requires documentation & support as an alternative, and must be approved by the AHJ. (IBC 2018 104.11)
Fair warning - these sprinklers are roughly $400 each, and have major restrictions for their use (including specific sprinkler placement dimensions and glass requirements).
Window-Style Sprinklers (by Tyco) can provide up to a 2-hour rating for a fire barrier. With wider application, these sprinklers also come with a significant list of limitations outlined in the product listing.
Passive vs. Active Systems
Passive fire protection requirements, such as the fire-resistance ratings of fire partitions, fire barriers, and fire walls, are required by code to limit the spread of fire.
The term 'passive' is given as no intervention or dynamic activity is required in order for the system to function. Fire partitions, barriers and walls have a long history of successfully extending longevity of buildings in a fire, limiting spread, and increasing the ability of people to defend in place or escape a fire.
Active systems are identified by a dynamic "action" that is required in order to function effectively. Automatic fire sprinkler systems are one type of active fire protection system, which require open valves, clear pathways, and in some cases the electrical and mechanical operation of fire pumps.
Point-Counterpoint For & Against Fire Sprinklers for Passive Requirements
This area of application isn't without controversy. There's opposite viewpoints on whether sprinklers should even be used as an alternative to passive fire protection. Here's a summary of the pros and cons:
Use of sprinklers in conjunction with glass can afford many architectural opportunities without the expense of rated glazing, but restrictions are extensive, such as ensuring no combustibles are adjacent to the glass
The Common Misapplication
I’ve often heard architects ask about using “water curtains” or “deluge sprinklers” when they have a rated fire barrier and are looking to incorporate a window.
The request is commonly for "closely spaced" standard sprinklers to comprise a 1-hour or 2-hour fire barrier.
I’m fairly confident that some part of me dies inside each time I hear either term - mostly because I know the education effort that always has to follow.
The Basis for Closely Spaced Sprinklers
The basis for standard, closely-spaced and located near glass, is provided in the International Building Code specifically for the enclosure of atria.
An atrium is specifically an opening that connects two or more stories and is one method of interconnecting multi-level spaces and acknowledging vertical openings with fire safe goals in mind.
Atrium spaces are unique in that they require fire sprinkler protection, a fire alarm system, and a smoke control system. All three of these components work in conjunction with each other to detect fire early in the process, notify occupants, and keep smoke to a manageable level while occupants escape.
The International Building Code allows “closely spaced” sprinklers to be used with glass (with limitations) in lieu of a 1-hour enclosure specifically because of the other systems already provided for life safety. (IBC 2018 404.6)
Misapplication for Non-Atrium Spaces
While this section for atrium spaces has existing for some time, what has not existed in the building code has been the provision for closely spaced sprinklers to equate to 1-hour fire resistance rating. To put it simply, a documented basis for such an arrangement doesn’t currently exist.
Could it be proposed as a code alternative to a 1-hour fire barrier? Perhaps. But even without being an AHJ, I would question what technical evidence would support the use of closely-spaced sprinklers to be used in lieu of a 1-hour fire barrier.
If I were an AHJ and closely-spaced sprinklers were proposed as a code alternative, I’d require a fire alarm system and a smoke control system for the space – just as is required for the atrium arrangement.
Casual (Sloppy) Design
Unfortunately, in some jurisdictions there’s not enough resources and/or education for code officials and plan reviewers to monitor and police applications like this.
Locally, I know of several jurisdictions who would immediately (and correctly) pounce on issues like this. I also know others where there is total reliance on the engineer for code compliance and proper design as there hardly is a plan review process.
This sloppy design causes issues for everyone, especially for me when I have to be the bad guy and educate an architect or general contractor on future jobs. It's the common excuse of "that's what we did on the last job" that of course justifies continuing down the wrong design path. This is one reason I really enjoy working with knowledgeable and thorough AHJs as opposed to more "hands-off" jurisdictions.
Free PDF Companion
Download our free PDF comparison between these three applications, with major design implications outlined.
I'm very interested in what your experience has been with the use of sprinklers to meet passive window fire protection requirements.
Help us by sharing your experiences on the topic in the comments section below. I look forward to the discussion.
References & More Reading
Arsenault, Peter. “Window Sprinklers as an Alternative to Fire-Rated Glass.” Continuing Education Center, Tyco, continuingeducation.bnpmedia.com/courses/tyco/window-sprinklers-as-an-alternative-to-fire-rated-glass/3/.
Kim, A.K., and G.D. Lougheed. “Fire Protection of Windows Using Sprinklers.” Construction Technology Updates, 15 Mar. 2018, www.nrc-cnrc.gc.ca/ctu-sc/en/ctu_sc_n12/.
Model WS-5.6 K-Factor Specific Application Window Sprinklers, Horizontal Sidewall and Pendant Vertical Sidewall. Tyco Fire Products Research & Development, 2016, Model WS-5.6 K-Factor Specific Application Window Sprinklers, Horizontal Sidewall and Pendant Vertical Sidewall, www.icc-es.org.
Tyco Window Sprinkler, tyco-fire.com/index.php?P=detailprod&S=6200.
I've heard that in order to publish on the internet all blog post titles must have a gripping click-bait title. This was my best attempt. Sorry to disappoint, but there is no love story here.
Things are back on track this week - the last got a little busy at home last week when my wife and I welcomed our third child to the family. Even with the third, it's amazing how much joy and motivation kids can bring with their arrival.
Needless to say I didn't have a whole lot of productivity last week, but I'm very glad you've tuned in. This week we're exploring requirements and challenges of sprinkler protection near overhead doors.
Sprinklers are required under "fixed obstructions over 4 ft (1.2 m) in width." (NFPA 13 - 2002-16 188.8.131.52.1, 2019 184.108.40.206.1)
One common application for this code section is overhead doors in the "open" position. Annex material even specifically references overhead doors as an applied example of this requirement.
Sprinklers are required where the horizontal projection of an overhead door exceeds 4-feet.
Application of the 4-ft Obstruction Rule
If the overhead door doesn't create an obstruction over 4 feet (1.2 m) in width, then a sprinkler is not required to be provided beneath the door. This dimension is typically applied in the horizontal dimension only, and is measured as the horizontal projection of the edge of the door away from the wall.
Depending on how creative things want to be architecturally, sprinklers can be avoided beneath overhead doors when the door assembly doesn't create a 4-foot horizontal obstruction. This can be the case with small coiling doors, door tracks that only run vertically up a wall, or a combination of vertical and horizontal tracks that don't project more than 4 feet out away from the wall.
Hanger & Supporting Challenges
NFPA 13 does not specifically address support for sidewall or upright sprinklers below an obstruction, but similar requirements can be extracted from criteria on pendent sprinklers served by branch pipe above a ceiling.
If a sprinkler's horizontal steel branch pipe feed is greater than 1'-0" for systems with 100 psi or more, or greater than 2'-0" for any steel system, then a hanger is required to support the armover (NFPA 13 2002-16 220.127.116.11, 2019 18.104.22.168).
This presents a natural challenge as the door track is typically only designed to support the forces of the door and is not considered to be building structure capable of supporting the sprinklers, pipe and fittings. While it's very common for installers to attach the hanger to the door track, many see this as a violation of the hanging rules of NFPA 13.
Supporting sprinklers beneath the overhead door can be a challenge due to the height differences between the door and the ceiling/roof structure above.
Drainage & Dry Systems
Protection beneath overhead doors ramps up to another level of difficulty when used in dry systems. If a sprinkler beneath an overhead door on a dry system traps water, there needs to be a means to drain the trapped water and for dry systems in an unheated area, would require an auxiliary drain and drum drip.
While this might not present a challenge with a single overhead door, multi-bay vehicle buildings could wind up having a low-point drum-drip for every or nearly every other overhead door.
Aside from the cost, these drum drips are a maintenance nuisance as failure to drain these on a regular basis could result in a freeze and rupture of the drain assembly.
New Guidance on Sprinkler Position & Types Below Obstructions
Fortunately - in an update that I find very helpful - the latest edition of NFPA 13 now addresses where sprinklers can be located beneath obstructions.
Sprinklers are required to be either located beneath the obstruction, or with their deflector no more than 3 inches off the side of the obstruction (see below). This was clarified in 2019 based on fire testing & research.
New guidance for sprinkler protection beneath obstructions - new to the 2019 edition of NFPA 13.
Where a sprinkler is adjacent to the obstruction and not directly beneath, it must be an "intermediate-level rack type" (NFPA 13 2019 22.214.171.124.1.3). These sprinklers are provided with a shield that prevents inadvertent cooling from sprinkler discharge above (the shield is ineffective and not intended to help "collect" heat).
What tips & tricks have you come across when dealing with sprinkler design around overhead doors? This site is created to start the discussion. Add your questions, tips & tricks in the section for your comments here.
Find this article interesting? Get more of my weekly articles & resources, for free, by subscribing here.
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Joseph Meyer, PE, is a Fire Protection Engineer in St. Louis, Missouri. See bio on About page.