Building Fire Alarm System vs. Household FA System

[iggy2]

For a multi-story apartment building in MA, the IBC-2009 requires a fire alarm system (FAS) for the building. A household fire alarm system (HFAS) is also required for each dwelling unit (apartment) in the building.

NFPA 72-2010 18.4.3.1 requires that the system provide 75 dBA audible alarm signals in all areas of the building "required to be served by the system" (the FAS). This is accomplished in the common areas of the building via horns in the corridors, lobbies, and other common areas.

The same is generally true of the HFAS - each HFAS must produce 75 dBA in the dwelling unit. The audible alarms are are made by sounder bases on the smoke detectors in and outside each bedroom, which all sound if one detector goes in alarm. (The sounder base would certainly give 75 dBA in the bedroom.)

So the FAS and the HFAS serve two distinct areas; the former serves the common areas and the latter serves the dwelling units.

Now - here's the question - Must the FAS provide 75 dBA audible signals in the dwelling units???

With an arrangement we see commonly, the FAS corridor horns would NOT provide 75 dBA in the bedrooms, or even in some cases, anywhere in the dwelling unit. But I would argue that the HFAS provides this function of 75 dBA in the dwelling unit - not the FAS.

Does anyone agree or disagree???

Thanks.

 

[dhalleron]

I cannot speak for code in MA.

If there is a fire in the corridor you are going to need to evacuate all of the dwelling units. The FAS is not there just to help people who are hanging out in the hallway. Is your HFAS also activated by the FAS? Normally it is not and then in that case you would need audibles in the dwelling unit that are controlled by the FAS.

One might have an argument with an AHJ as to whether or not the dwelling units are required to be covered by the FAS. I talk to many installers that failed inspection because they installed only one horn connected to the FAS in the living room of a dwelling unit in an apartment and it was not loud enough in the bedroom.

 

[MichaelGP3]

"With an arrangement we see commonly, the FAS corridor horns would NOT provide 75 dBA in the bedrooms, or even in some cases, anywhere in the dwelling unit. But I would argue that the HFAS provides this function of 75 dBA in the dwelling unit - not the FAS."

I'm uncomfortable with this reasoning.

Think hybrid; see if your AHJ will approve. One low voltage system - fire alarm initiating devices in common areas sound/strobe throughout the building. Smoke detectors going into alarm inside dwelling units sound/strobe only within that apartment, all devices supervised by the FACP. A system like this could be programmed to cause apartment smoke detectors to behave as general alarm devices via flip switches on the panel (one switch per apartment, say), increasing protection to other building occupants when an apartment is vacant or the tenant is on vacation.

 

[iggy2]

"One might have an argument with an AHJ as to whether or not the dwelling units are required to be covered by the FAS."

That is exactly what we are trying to avoid. But I do not see any clear code to definitively answer this one way or another...

"Think hybrid"

What you have described is, more or less, what we have designed. The question is, are audible devices from the FAS required within the dwelling units, since the dwelling units are protected by the HFAS?

BTW, the HFAS detectors cannot, per code, set off the FAS. They must only alarm within the dwelling unit. They are also not required to notify the local FD, despite that many FDs try to force this anyway. Think of any other single family home - the smoke detectors there do not notify the FD, unless the Owner CHOOSES to havbe a monitored system. But there is no code requirement to supervise the single/multiple station smokes in a dwelling unit.

 

[gadfly56]

I do not find anything in the IFC/IBC 2009 that require the two systems to talk to one another. And it is true that you don't want the building FACP to ring everything if one apartment dweller has scorched some pop corn.

That said, it is easy to achieve all ends with a high end panel like Siemens, but you'll need a waiver from the AHJ if you go by the 2009 editions of the IFC/IBC to eliminate the HFAS.

Each apartment has smoke/heat detectors with sounder bases as needed for proper coverage. When any one of the detectors go off, all the sounder bases IN THAT UNIT ONLY are activated via logic. If a hallway detector or pull station or sprinkler is activated, the common area notification and all the sounder bases in all the units are activated. It will be spectacularly noisy. And you don't need to flip any flipp'n switches.

The downside of course is system maintenance. Imagine trying to get into every single apartment once or twice a year for inspections. And it wouldn't be hard for a tenant to do something intentional or un- to compromise the system. Which are two reasons, I suspect, why the code calls for separate systems.