Image source: The Home Fire Sprinkler Coalition
If you've decided to install fire sprinklers in a new or existing home, great choice. These invaluable life safety systems are designed to give occupants time to escape from a fire, and statistics compiled by the National Fire Protection Association (NFPA) show that they reduce the rate of residential fire deaths by 81% while lowering property damage by 58% or more.
Now that you've made the decision, you likely have questions, including: How are home fire sprinklers installed? What types of systems are there? Can I retrofit fire sprinklers into an existing home? And how much will it cost?
Fortunately, NFPA has simplified the guidance for installing home sprinkler systems. While commercial systems are governed by complex installation, inspection, and maintenance requirements, NFPA specifically created its "design and installation standard" for home sprinklers with a focus on "the practicality of simplified design and installation techniques, homeowner acceptance of the technology, and overall system reliability." The result is a much easier process outlined in NFPA 13D: Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes.
This series of blogs from QRFS will cover the essentials of a home fire sprinkler installation, including the proper materials, functional requirements, and maintenance needs. Local building and fire safety codes may add requirements (more on that later), but NFPA 13D is considered the basic national standard for these systems. We will simplify NFPA guidelines, explain the installation or retrofit process, and cover many of the decisions an average homeowner will have to consider when choosing a system or its components.
Before proceeding, are you simply interested in purchasing system components for your planned home sprinkler system? Feel free to jump directly to QRFS' selection of residential system components or use the search bar above.
How Home Fire Sprinkler Systems Work
Regardless of which type of home fire sprinkler system is installed, they are all designed to fulfill the same purpose. NFPA prioritized saving lives over property when creating the 13D standard; residential fire sprinklers are explicitly intended to give occupants time to escape from a home during a fire. This priority led to guidelines that all home systems should have "a 10-minute stored water supply and an adequate local audible alarm." That said, home fire sprinklers often significantly reduce damage to a home, and, in many cases, they are able to completely control a fire.
Every system will have specific water flow and pressure specs to meet the 10-minute water demand, and these rely on a combination of factors:
- The size (square footage and height) of your home, and the length of pipe and number of sprinkler heads that must be installed to provide minimum water coverage. Obviously, a larger, taller home will need a bigger system and thus have a higher cost.
- The type of pipes that are used; specifically, their material and diameter.
- The water source, and whether it naturally provides enough pressure to meet flow requirements or it needs to be amplified by a pump.
Every system relies on a network of piping that is run vertically (within the walls and sometimes in closets) and horizontally (within ceilings or attics). At periodic points in the network, sprinkler heads will be joined to the pipe to deliver water from the ceilings and/or walls. A contractor will install a sufficient number of sprinkler heads to completely cover necessary areas (more on that later), with each one no less than 8 feet apart.
The vast majority of home sprinklers are "wet" systems in which the water that feeds the sprinklers is always in the network of pipes. The way they work is surprisingly simple, reliable, and effective, and explains why some version of this automatic technology has been in use since the 19th century.
Residential sprinkler heads basically act as plugs in the network of piping that contains pressurized water (or air, in fewer cases). Each head has a trigger that is usually either a glass tube filled with a heat-sensitive liquid, or a metal link that is soldered together. When a fire starts in a specific room, it will begin throwing off heat that moves toward the ceiling. Once the temperature around the sprinkler head reaches a certain point (usually 135°F to 170°F), the heat either causes the soldered link to melt or it causes the liquid to shatter the glass tube. This 'breaks the seal' on the plug in the piping and lets the water rush out. The water is then automatically fanned across the room when it hits the small wheel at the end of the sprinkler head. To learn more about how a fire sprinkler's thermal element works, check out this article.
Components of a Residential Sprinkler (Image Source)
This design is extremely simple, effective, and reliable. There are no computers, electricity, or other complex triggers involved; just heat causing a mechanical response. This heat-activated design avoids false alarms like the ones that plague some smoke detectors and limits the deployment of sprinklers to only the room or rooms that are on fire.
Two Major Residential Sprinkler System Types
Home fire sprinklers have numerous design and component options - including different types of piping and sources of water - but all systems fall into two major categories: standalone and multipurpose.
1. Standalone fire sprinkler system: Uses a network of piping that is separate from the piping used in the home's plumbing system. Both the standalone sprinkler and plumbing systems can draw from the same water supply, or a standalone system can draw from its own supply, such as a dedicated water tank. If a standalone system uses the household water main, there will be a "T" connection, called a "riser," that exclusively feeds the sprinkler system.
Standalone systems can have a wider variety of parts and materials than multipurpose systems, including metallic piping options and extra safety or testing components. They also tend to have more complex installation and maintenance requirements. They do have some distinct advantages in certain scenarios, however, such as working well in areas without a sufficiently pressurized water supply.
Residential Sprinkler During Rough-In (Image Source)
2. Multipurpose fire sprinkler system: Integrates with a home's plumbing system; the sprinklers are fed off of the same water source and cold-water plumbing pipes that service other fixtures in the home. Because they use the same pipes and fewer fittings and connections, the installation costs and complexity tend to be less with multipurpose systems. In addition, they require less maintenance and they are arguably more reliable, as a homeowner will usually know if a multipurpose system has a problem - as any issue will also likely impact the regular plumbing that is used every day.
That said, multipurpose systems may not be an option for homeowners who are looking to retrofit sprinklers into their house, as these systems require carefully planned hydraulic calculations that account for water pressure, the size of the system, and even the diameter of piping needed to meet specific flow requirements.
Finding a Qualified Fire Sprinkler Installer
The most critical aspect of any new home installation or retrofit is choosing a qualified contractor to install the system. While the installations themselves are not much more complex than putting in plumbing, a sprinkler contractor must have the expertise to design the system with hydraulic calculations that ensure there is adequate pressure and flow. The following section gives a brief introduction to the selection criteria for a sprinkler contractor; if you'd like more information, check out our Guide to Selecting a Fire Protection Contractor.
An experienced contractor will use these calculations to determine the extent of the system and the parts used, and then create scale drawings that are submitted to the local authority having jurisdiction (AHJ) for approval. These documents are usually submitted during the permitting process for new installations or, in areas that require it, the permitting process for renovations.
In addition, a qualified local contractor will have specific knowledge of any local or state codes that go above and beyond the NFPA13D standard:
- For example, while NFPA does not stipulate the use of backflow preventers in all standalone systems, many jurisdictions do. These one-way valves prevent the stagnant water in the sprinkler pipes from flowing back into and polluting the potable water supply. Backflow preventers reduce available downstream water pressure, however, and a knowledgeable contractor will account for this when designing the system.
- In a contrasting example, the Philadelphia water district requires that all residential systems supplying dedicated sprinkler heads have a connection from the sprinkler system to the toilet tank that's furthest from the water supply. This removes the need for a backflow preventer, because every time that toilet is flushed, it draws water through the fire line to keep the water fresh.
The bottom line: A knowledgeable local contractor will account for these types of local requirements when designing a system.
Residential Contractor During Install (Image Source)
Some states require fire sprinkler contractors to have certifications. In California, for example, the Business and Professions Code and the Contractors State Licensing Board (CSLB) mandate that only contractors with a C-16 (Fire Sprinkler) Contractor's License should install systems. In addition to making sure that an installer has any needed government certifications, you'll also want to verify that they are bonded and insured, and you may want to ask for references and check their background for any outstanding judgments or claims, as well as any citations from OSHA or other government authorities.
Professional associations are a great resource for finding qualified contractors in your area:
- You can contact the American Fire Sprinkler Association to find members of their Quality Contractor Program.
Finally, choose a contractor who you are comfortable with - one who is willing to answer all of your questions and clearly communicate the entire process. Be sure to fully communicate with them in return. Tell the installer about any special considerations or planned changes to your residence, especially during a retrofit, and thoroughly review the plans they create.
For example, if you intend to knock out a wall or install a wall cabinet in a certain room, it may interfere with the intended spot for a sprinkler and compromise water coverage. Good contractors will appreciate this communication and work to minimize any disruption caused by the process.
"A retrofit project with any occupied building … I think the most important thing is having good, open communication with the homeowners, and to describe to them exactly what you're going to be doing and where you're going to be working," says David Walencewicz, a professional engineer and the owner of P&J Sprinkler Company, Inc. in Hartford, CT.
"Doing any kind of residential retrofit, the key points to think about, in your planning, [are] the aesthetics, how the sprinkler system is going to look to the homeowner. You want to make sure you can conceal as much piping as possible. If you can go into a wall channel and actually pipe two or three sprinklers from it, that's great because you can create the least amount of demolition and reconstruction work."
Check out this Video from the Home Fire Sprinkler Coalition about Retro-Fitting Your Home
In the next installment of A Guide to Installing Home Fire Sprinklers …
In part two of this series, we'll take a look at the individual components of a residential fire sprinkler system, including how designers determine the right water supply, the varieties of pipe that can be used, and the different types of sprinklers that are available.
If you're looking to buy components for your new or existing home fire sprinkler system, QRFS offers a wide range of residential fire sprinkler system components.
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