is the intent of NFPA 72 for new apartments to have low frequency horn and strobes in every unit or just the unit for hearing and visual disabilities.
NFPA 72 tells you how to install a system.
You would first start with building or fire code adopted to see where audio devices are required.
If they are required in sleeping areas, than no matter what, they have to be low frequency. But, also depends on which edition of 72 is also adopted.
PLUS, there is also an interpretation that the living room is considered a sleeping area, so low frequency also installed in living rooms.
Normally in hearing loss units, strobes are installed.
OHHH I am not an engineer, so you can discount my reply if you want
There is always more to add from the discovery of facts that change the parameters.
If your question is concerning the detection of fire within the apartments, then the strategies of 2018 NFPA 101 Chapter 30 New Apartment Occupancies may be of some help to you.
I can not speculate what the local building codes and regulations are for fire detection in new apartments. I would image that permission to use a fire alarm system connected smoke detectors within an apartment would require special approval by the AHJ of the local building codes and regulations.
Under the premise NFPA 101 tells you when to install a system and NFPA 72 tells you how to install the system, Section 220.127.116.11 requires smoke alarms installed in accordance with Section 18.104.22.168 in every sleeping area, outside every sleeping area in the immediate vicinity of the bedrooms, and all levels of the of the apartment including the basements. This section modifies the requirements of Section 22.214.171.124.1 to provide a fire alarm system within the apartments in the building. According with this Section, smoke alarms required by Section 126.96.36.199.1 must be installed in accordance with NFPA 72 with the modifications to NFPA 72 in Section 188.8.131.52.3, 184.108.40.206.4, 220.127.116.11.6, or 18.104.22.168.7. There were no requirements within Section 22.214.171.124 and the referenced section 126.96.36.199 for audible notification appliances producing low frequency alarm signals.
Chapter 29 of the 2016 NFPA 72 have the provisions of how to install smoke alarms.
Section 29.3.8 has provisions for notification appliances provided in the sleeping rooms for those with hearing loss.
This section is conditional on the fact the audible notification appliance producing a low frequency alarm signal is required by governing laws, codes, or standards for people with hearing loss and a provided voluntarily to a person with hearing loss. One of the federal laws that I think of is the Americans with Disabilities Act (ADA) which became law in 1990. I can not speculation the what the local building codes and regulations are for audible notification appliances but I can not speculate that the notification appliance must produce a low frequency alarm. You will need to contact the US Justice Department to get the answer for that federal law. NFPA seems to have left when to accommodate people with hearing loss within the apartment to others .
With all that said. I am sure this creates some uncertainty of the codes for audible appliances for not knowing the people that will rent the sleeping rooms. You should consult the local building codes and regulations. However, if I were the designer, if those regulations appear ambiguous for that particular apartment, I would not hesitate to install audible notification appliances producing low frequency in the sleeping rooms. You could indemnify your bid without them, but that may not be adjudicated it the courts.
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