Are residential sprinkler systems common?

Factual Questions
1

My county just passed a bill requiring all new home construction to include residential sprinkler systems. I have never seen a home with a sprinkler system, and don’t know how common they are. My question is, is this a good idea? (That is, beside the fact that they are raising constructions costs at a time when homes are difficult to sell to begin with.)

It seems to me that most houses do NOT catch on fire. Most mechanical systems, however, do tend to have some kind of a bug from time to time. Besides fire, one of the most destructive things I can think of for my house would be large volumes of water.

How likely would it be for a home sprinkler system to go off by accident or sensor failure? If I had a small grease fire in my kitchen, would my whole house get flooded, or do most home systems have separate zones for dispensing water? Finally, just how much would such a system add to the cost of my home?

2

Depends on how good the contractor is who does the work and. Commercial buildings seem to have these things w/o much harm being done.

Where do you live? I know that where I live (Santa Clara County, CA), you are required to install such a system if the nearest fire hydrant dispenses less than 1000 gal/ minute. I believe that is typical of a 4" line, and that the newer lines tend to be 6" (going from memory, so I could be wrong).

3

I live in Anne Arundel County, Md. The bill just passed yesterday, I believe.

It seems like commerical properties not only have them, but have to have them inspected periodically. It would seem that would be another expense for the home owner, and, perhaps, another reason NOT to move to Anne Arundel County, Md.

4

Residential fire sprinkler systems cost about $1 per square foot. The sprinkler head contains a cap held shut by an alloy link (or sometimes a glass bulb) that will “fail” at the designated temperature. Thus, only the sprinkler in the fire area can go off. The temperature at the ceiling must exceed the design temperature for a specified period of time before the sprinkler goes off, so I’m pretty sure your “small grease fire” wouldn’t even begin to get there.

5

Missed edit window…

It depends on how your local code was written, but I’ve never heard of mandatory inspections on a private residential system – your risk, your call.

6

I don’t know if they’re required in my county, but homes in this neighborhood were all built with sprinklers about 20 years ago. We are in an unincorporated area and we don’t have a staffed fire department - we have a volunteer force and support from nearby refineries’ fire departments.

Aside from some added peace of mind, we do get a discount on the homeowner’s insurance.

As for water damage from a broken or mis-fired sprinkler head, that’s easily handled by shutting off the water. Last I looked, fires don’t have handy valves to turn them off.

Looks like requiring sprinklers in all new residential construction is about to be adopted into the national building code.

7

Assuming someone is home. Which, in many families, is often not the case for long periods of time during the day.

8

Residential sprinklers - a subject near and dear to my heart.

Firstly, there are three different sections of the National Fire Codes that we are dealing with. The first is NFPA 13, Standard for the Installation of Sprinkler Systems. That covers most systems. There are two other sections, though, that cover what we’re talking about. 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. The 13D systems are what we’re dealing with in this case.

NFPA 13D was first published in 1975, after a two-year writing and vetting process. Residential sprinklers have been available since the late 1960s. NFPA 13 (for the big systems) has been around since 1896.

Residential sprinkler systems are not exactly like those found in commerical and other large buildings. Think of them as a much smaller cousin. They do not have to meet nearly as many requirements as a commerical system, thus they are a boatload less expensive.

  • A regular NFPA 13 system needs a minimum of a 6" water main and a long duration water supply (upwards of 3 hours, depending on the size of the system). A 13D needs no water main (so you can use a well) and a 10 minute water supply.
  • The water flow in a NFPA 13 system is calculated based on the expected hazard in the building, how much water per square foot is needed for that hazard, and how many square feet that that quantity of water is needed on. You can expect capacities greater than 1500 gpm for an NFPA 13 system. For a 13D, you generally only need to provide the flow capacity for two sprinkler heads.
  • Speaking of sprinkler heads, a normal NFPA 13 system needs a minimum of 1/2" heads, flowing about 35 gpm at 50psi. They can go as big as 1-1/2" heads flowing upwards of 250 gpm in some applications like high rack storage warehousing. A residential sprinkler head is designed to activate sooner (called a quick-response head), if it goes off sooner, the fire is smaller, and less water is needed. A residential head can have flows as low as 18 gpm.
  • Plastic pipe can be used in a 13D system (CPVC), you do not need black iron threaded or steel grooved piping like an NFPA 13 system.
  • No fire department connection (a hose connection for firefighters to add water to a sprinkler system) is required on a 13D system (although it’s a good idea to have one). It is requried on a NFPA 13 system
  • No special valving system is required on a 13D system (no alarm check valve, usually no backflow prevention, only one indicating valve, etc)
  • No outside alarm system is required (either a mechanical or electrical alarm outside to indicate the system is operating)

That’s off the top of my head. The list goes on, I don’t have the time to do a complete side-by-side comparison of the codes.

As was said above, they run about $1/square foot to install. Installation in new buildings, obviously, is much cheaper than in existing buildings. Here in Massachusetts, I’ve heard that starting in 2012 they’ll be required in all new construction. About time, if you ask me.

There are a couple of streets in my town where the developer chose to install residential sprinklers, and there are a number of individual houses elsewhere with them. I have not had to respond to a house fire in any of the sprinklered homes, but the fires I have gone to in unsprinklered homes would have been much smaller had sprinklers been present.

A fire in today’s homes can remove your exit choices in less than a minute from igniton, and can produce sufficient combustion byproducts to incapacitate anyone inside in two to three minutes. Smoke detection is (usually) great, but it doesn’t put water on the fire. Residential sprinklers buy you the time to get out of the house safely. When all is said and done, the fire may be smaller than it would have been, but that’s not the goal of a 13D system - it’s purely for additional evacuation time.

There are a few good videos on YouTube of residential sprinklers operating. I do like the PSA from Fresno, CA on the topic, too.

9

I’d still rather come home to a soaked room than a burnt-out husk.

Also, the sprinkler system will sound a bell when water’s flowing, and they’re easily tied into the home security system so the alarm company can call you and the fire department.

10

KCB165’s post covers it.

Residential sprinkler systems are becoming a lot more common. In MA I believe the current requirements for residential systems only apply if the structure contains 3 or more residences. At a future date it is expected to be required in all new construction. Many high end builders have already started including them.

You set off a commercial sprinkler its like opening a fire hose. The spray will blow through sheetrock in no time and drench everything near instantly. They are designed with the ability to put out fires.

Residential systems are much lower volume. They are more like a mist in comparison. The concept is lower the temperature in a room to stop a fire from spreading as quickly. The goal is only to allow occupants more time to evacuate.

They are an added expense and do pose a threat of accidental water damage to a home. That is weighed against their life saving potential. People will object to them for a while but I expect they will become as common as any other fire code requirement that’s been implemented in the past.