#100 – Residential Fire Sprinkler Systems: Guide to Installing Home Fire Sprinklers, Part 1

Hero image source: The Home Fire Sprinkler Coalition, an excellent resource for information about residential sprinklers.

Learn about the benefits of home sprinklers and the considerations when installing them

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 88% while lowering property damage by 62% or more.

Whether you’ve made the decision or are still on the fence about it,  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 much of the guidance for installing home sprinkler systems. While commercial systems are governed by fairly 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 covers 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 fundamental national standard for these systems. We 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.

Are you simply interested in purchasing system components for your planned home sprinkler system? Feel free to jump directly to QRFS’ selection of residential sprinklers or use the search bar above.

How residential 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 prioritizes saving lives over property in the 13D standard; residential fire sprinklers are explicitly designed to give occupants time to escape from a home. For example, this priority causes residential sprinklers to have specific traits — they go off faster and have unique spray characteristics. And it spurs various rules, such as 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 homes despite focusing on life safety, and, in many (many) cases, they are able to completely control or even extinguish fires.

Every system will have specific water flow and pressure specs to meet the minimum 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 pipes and the 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 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 installs 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 wet sprinklers work is surprisingly simple, reliable, and effective, which 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 or nitrogen gas, in the cases of dry systems). Each head has a trigger that is usually either a glass bulb filled with a heat-sensitive liquid or a metal link that is soldered together. When a fire starts in a specific room, it begins 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, depending on a sprinkler’s activation temp.), the heat either causes the soldered link to melt or 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 disc at the end of the sprinkler head, called the deflector. To learn more about how a fire sprinkler’s thermal element works, check out this article.

The main components of a residential sprinkler. Image Source: HFSA

This design is extremely simple, effective, and reliable. There are no computers, electricity, or other complex triggers involved; just heat automatically causing a mechanical response. This heat-activated design avoids false alarms like the ones that plague some home smoke detectors and limits the deployment of sprinklers to only ones covering a room or rooms that are on fire. This is an important thing to know, given Hollywood’s depiction of a bunch of sprinklers all going off at once. In truth, sprinklers’ deployment and any potential water damage are much more limited and focused on where they need to be.

Two major residential sprinkler system types

Home fire sprinklers have numerous design and component options — including different types of pipe material and sources of water — but all residential systems fall into two major categories: standalone and multipurpose.

1. Standalone fire sprinkler systems use 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 “Tee” connection leading into 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 slightly more complex installation and maintenance requirements, though only slightly. Standalone systems do have some distinct advantages in certain scenarios, however, such as working well in areas without a sufficiently pressurized municipal water supply.

Residential sprinkler during rough-in
A residential sprinkler in a standalone CPVC system during rough-in.

2. Multipurpose fire sprinkler systems integrate 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 a bit less maintenance and have one reliability benefit: a homeowner will usually know if a multipurpose system has a problem because 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 houses. Fire sprinkler 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, and there is less flexibility with existing homes. And though there are slight differences in the ease of installation and maintenance, both types of systems are pretty easy to handle. After all, NFPA standards aim to make things as simple as possible to encourage the use of home fire sprinklers.

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 or have access to the expertise needed to design the system with hydraulic calculations that ensure adequate coverage, pressure, and flow. The following section gives a brief introduction to the selection criteria for a sprinkler contractor. But you should also check out our guide to selecting a fire protection contractor.

An experienced contractor will use 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 those in 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
A contractor doing a residential installation. Image source: Delta Fire Systems 

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:

  • The National Fire Sprinkler Association (NFSA) has an online tool that allows you to locate NSFA contractors; you can also directly contact state chapters, such as the Florida Fire Sprinkler Association.
  • You can contact the American Fire Sprinkler Association (AFSA) to find the latest 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 about retrofitting a home from the Home Fire Sprinkler Coalition:

In the next installment of our guide to installing residential fire sprinklers …

In part two of this series, we take a look at the individual components of a residential fire sprinkler system, including how designers determine the right water supply 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 sprinklers and other components, such as residential risers.

Can’t find what you’re looking for? We still have numerous products not yet listed online or accessible through our network of partners. So if you have questions about residential fire sprinklers or need help finding an item, add a comment below, give us a call at 888.361.6662, or fill out our contact form and we’d be happy to assist.

This blog was originally posted at QRFS.com/blog. If this article helped you, check us out at Facebook.com/QuickResponseFireSupply or on Twitter @QuickResponseFS.

7 thoughts on “#100 – Residential Fire Sprinkler Systems: Guide to Installing Home Fire Sprinklers, Part 1”

  1. Thanks for helping me learn more about fire sprinklers. I didn’t know that a multipurpose system is integrated with a home’s plumbing system. I’m interested to learn if this could be ideal if someone has a pretty simple plumbing system so it can be managed easier.

  2. Exceptional Article! I think the best described article for the Sprinkler Systems. It is step by step so I get all answers to my questions and is very informative at the same time.

  3. I really appreciate all your help and support here ,moreover I wanted to know more about sprinklers and the mojor tools required to install sprinklers

  4. Good information the system should be calculated for flow to the 2 most remote sprinklers if anyone would like i have a simple spread sheet for this just email me. I’m retired F/F and spent 47 years as a contractor/designer.


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