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Residential Fire Sprinkler Systems – Now What?

October 17th, 2009

As featured in Plumbing Systems & Design Magazine, September 2009

It would be hard to believe that anyone who takes the time and makes the effort to stay abreast of events affecting their industry would not be aware of the monumental changes regarding the next edition of the International Residential Code (IRC) and fire sprinkler systems. However, just in case you accidentally picked up this magazine thinking it was Sports I Illustrated or you are in the waiting room of your doctor’s office and must choose between this magazine and Psychology Today, let me fill you in because you are already behind.

In September 2008, the IRC committee voted to include a new provision that requires single-family homes to be sprinklered. This, of course, has been the topic of articles, seminars, reports, and state legislation ever since, and through it all one thing is for sure: The installation of fire sprinkler systems in residential occupancies is here to stay. Challenges and amendments may have some impact initially, but I have learned one main thing during many years of being involved in the code-making process. Once something makes it into the book, it is very difficult to get it out, and with each edition that it remains, it becomes like curing concrete: The longer it sets, the stronger and more unmovable it will be.

YOUR OPTIONS
Now that this requirement is here, the question must be asked: “What are you going to do about it?”

You have a few options. The first is to ignore it and go on with business as usual—that is, if you still have a business. Let’s face it: With the economy shrinking like it has, the level of competition for the few available projects is very high, and many of us have experienced downsizing in one way or another. In fact, most of us are working to stay in business, much less thinking about growing one.

The second option is to recognize that while the construction market is smaller, an entirely new vertical has been opened. It is this option that presents a “glass half full” opportunity.

It has been reported that this new residential sprinkler market could conservatively create revenues more than $3 billion annually (see “Residential Fire Sprinkler Market Analysis“. That’s billion, with a B. It also is well documented that the fire protection industry will be strained to meet this demand as this new requirement grows by adoption.

The design and installation of residential fire sprinkler systems is not new to the fire protection industry, but it is new to the plumbing industry, which includes engineers as well as contractors. Who better to relieve that strain than those already familiar with residential construction and most of the materials associated with these types of systems but the plumbing industry? While residential fire sprinkler systems are not as complicated as commercial systems, there are major differences in the design approach as well as some of the equipment used. If this second option has sparked your interest and you have the energy to pursue something that may take time and some investment to master, I would encourage you to read on.

The rewards are plenty, but it will not be easy.

A LITTLE BACKGROUND
In brief, the history of residential fire sprinkler systems starts around 1930, but it did not really become formal until the 1950s and early 1960s. This was due predominately to the development of a new installation standard and, soon after that, the emergence of several new types of sprinkler technologies responding to the growing concern over residential fire loss. Manufacturers and contractors alike began to envision the immense benefits that these systems would provide toward alleviating the ongoing tragedy of human loss due to residential fires. Money and market share took it from there.

One of the first milestones identified during these early events was the development of an installation standard, similar to the commercial standard for installation, called NFPA 13: Standard for the Installation of Sprinkler Systems. Along the course of the standard development, creators recognized that the two major occupancy groups already established in the building codes would have to be addressed. These two groups are single-family and multifamily.

As such, we ended up with two installation standards. They were conveniently named NFPA 13D: Standard for the Installation of Sprinkler Systems in One- and Two family Dwellings and Manufactured Homes and NFPA 13R: Standard for the Installation of Sprinkler Systems in Residential Occupancies Up to and Including Four Stories in Height. Once these standards became available, the adoption process began, which lead to the historic September 2008 vote.

HOW DOES RESIDENTIAL SPRINKLER SYSTEM DESIGN DIFFER FROM COMMERCIAL?
Having these two standards in hand, you easily could conclude just by looking at them that together their thickness is not more than the single Chapter 8 of NFPA 13. Do not let that fool you. There are significant differences in the approach of residential design compared to commercial. Equally significant is the difference between NFPA 13D and NFPA 13R. It is these differences that need the most press and should be the starting point for anyone who is interested in learning more about residential fire sprinkler system design and installation.

Let’s start by focusing on NFPA 13D.

figure1_sprinklers

SPRINKLER HEAD LAYOUT
First and arguably the most important aspect of residential fire sprinkler systems, aside from water supply, is sprinkler head layout. Hundreds of different types of residential sprinklers are available today (see Figure 1), each with their own specific characteristics, including orientation, temperature rating, spray pattern, and minimum water and pressure demands. In fact, one of the most time-consuming tasks of residential design is finding the right head for the right application.

You easily can end up with four, five, or even more different types of heads in one home. Hence, you easily could spend as much as 50 percent of your design time just getting the sprinkler heads laid out.

That said, a closer look at what this process involves would be helpful.

One concept to understand in residential sprinkler head layout is the philosophy or goal behind the rules in the standard. What are we trying to accomplish? Commercial systems have a spectrum type of philosophy, if you will, spanning from life safety to property protection as its goal. Depending on the occupancy type, the goal may weigh more toward life safety than property protection or vice versa.

That’s not so in residential design. The goal for residential design is one thing and one thing only: life safety! The standards are written around the goal of giving people enough time to get out. While residential sprinkler system statistics conclusively prove that sprinklers provide a high level of property protection, the truth is that we do not care about the dwelling.

The rules and standards in NFPA 13D and NFPA 13R are based on the concept of sprinkler heads activating early in the fire growth, providing wall wetting and air cooling for 10 minutes (the required water supply duration) such that the rooms are tenable enough for evacuation. If this is the goal, it is obvious why the sprinkler head type, spacing, and location are so critical. This cannot be emphasized enough. You may find a sprinkler head that fits your needs on the very first cut sheet you open, but 28 years of experience tells me that this rarely happens. When it does, I am very skeptical about running off with my first choice without researching others just to make sure.

Another concept of residential sprinkler layout involves understanding the part that orientation and application play. As I stated earlier, there are hundreds of heads to choose from, so selecting the right one for the job means you first need to evaluate the space you are protecting. You will need to answer questions such as:

• Is the ceiling flat or sloped and if so, at what pitch?

• Are there any soffits, pockets, or other ceiling configurations that would inhibit the goal of early activation with high spray patterns?

Answering these questions will narrow your selection of sprinkler heads very quickly.

The process of laying out sprinkler heads involves a mix of rules from the standard, either NFPA 13D or NFPA 13R, and those found in the manufacturer’s data. Most of the time the manufacturer’s data supersedes the minimum requirements in the applicable standard, which is acceptable in that every NFPA standard includes in it an equivalency clause such as this: “Nothing in this standard is intended to prevent the use of systems, methods, or devices of equivalent or superior quality, strength, fire resistance, effectiveness, durability, and safety over those prescribed by this standard. Technical documentation shall be submitted to the authority having jurisdiction to demonstrate equivalency. The system, method, or device shall be approved for the intended purpose by the authority having jurisdiction.”

The challenge then becomes to accurately locate the sprinkler heads in accordance with the manufacturer’s requirements as well as any applicable minimums found in the standard. The effort required for this process is dictated by the complexity of the space.

As mentioned before, several factors determine the final location for a sprinkler head, and the designer must be familiar with these.

figure2_layout

For example, let’s evaluate a simple layout in a single-family, single-story home using NFPA 13D. Figures 2 and 3 represent identical floor plans with two different head layouts. Both are in accordance with manufacturer’s data and NFPA 13D.

figure3_layout2

Notice the difference in head types as well as the head count.

System economics is driven predominately by head count. However, do not take this to mean that less heads always means less expensive.

Depending on the type of construction, the labor to pipe Figure 2 easily may offset the cost associated with the difference in head count shown in Figure 3. Keep in mind that these two layouts are based on flat ceilings, no ceiling fans or light fixtures, no soffits or coffered ceilings, control over the locations of heat vents, and geographically located in the southern half of the United States where freezing conditions are not an issue. Certainly it appears easy just looking at the finished layout, but all it takes is one or more of those previously mentioned conditions to exist for the layout to change drastically.

Also included in this head layout process are the rules involving the rooms or spaces requiring and, more importantly, not requiring sprinkler head coverage. Dealing with exceptions in codes and standards is always a challenge because the shades of gray show up.

This is usually not as prevalent in single-family, NFPA 13D systems as it is in NFPA 13R and NFPA 13 systems; however, where there is an architect, there is always more than just black and white. Along with the exceptions to coverage are those construction or architectural features that neither the standard nor the manufacturer addresses, and contrary to popular thinking, this is not more common in custom homes than tract housing. These types of situations make head layout very challenging and require assistance from those more familiar with the industry and developed resources such as fire protection engineers and manufacturer technical service departments.

RESIDENTIAL SPRINKLER HEAD LAYOUT IS AN ART
It can be mastered by anyone who has desire to learn. The better your understanding and working knowledge of residential construction techniques and materials, the more proficient you will be. I would encourage anyone interested in pursuing this industry to first purchase a copy of NFPA 13D and NFPA 13R. Second, find online resources including blogs and sprinkler industry articles, webinars, and books that will help you grow in your understanding and knowledge of residential sprinkler design and installation. Third, and probably the most important, is to join the sprinkler industry associations.

sprinkler_resources

I have very little patience with and am skeptical of anyone, no matter how long you have been designing or installing toilets and sinks, who is going to get into this industry and not take it seriously.

This goes for engineers and contractors alike. Fire sprinklers are not something with which you dabble. I am very critical when it comes to engineers practicing outside of their discipline and contractors who think that pipe and water is all that there is to it!

If you have decided to participate in this growing industry and work for a piece of this huge pie, then welcome, but do it right! Getting involved in an association is one way of ensuring your success in this new venture. These associations are stocked full of resources and technical staffs who are looking for ways to help you do just that.

In my next article I will compare the two residential standards, NFPA 13D and NFPA 13R, and highlight the major differences between them.

Steven Scandaliato is a Fire Smarts Faculty member and Principal at SDG, LLC, a fire protection design and consulting company. With over 23 years of fire protection engineering, design and project management experience he holds a Level IV certification from NICET in Fire Sprinkler Layout and serves as a member of the NFPA 13, 101 and 5000 committees.