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Fire Alarm System For Mixed Use Occupancy Apartments & Mercantiles

Question asked by pomsceojosephm on Jul 12, 2018
Latest reply on Jul 31, 2018 by milt.werner

Hi everyone,

             My name is Joe, I am Nicet certified level IV in fire systems and there are a few things that become confusing and a particular project I am looking for clarification from the helpful engineering experts here.

In CT we use the IBC to identify the occupancy use. For new construction we use the IBC section 907 for fire alarm requirements. For existing structures we use the NFPA-101 2012 and it's corresponding chapters for"existing" to determine fire alarm requirements. For existing structures that are undergoing a change of use or community we use the corresponding "New" chapters. I get mixed up in mixed use and here are the facts about the building:


Mixed use occupancy:

  • 2 Story building.
  • 7826 Sq Ft (First Flr) 7826 Sq Ft (2nd Flr) 2948 Sq Ft (basement) total building: 18,600
  • Currently there is small building fire alarm system with 1 smoke detector in each of the mercantiles with no notification. The residential units have smokes in the hallway and notification in the hallway only which is not enough to create 75 dB at the pillow.
  • 5 Mercantiles (fish store, small pizza joint, barber shop, hockey sports shop, apparel shop) all of which are at grade level. There is a basement that extends from the hockey sports shop to the apparel shop.
  • 10 Apartments above all the mercantiles that share a common hallway (corridor) with a total of 3 stair exits (each hall end and in the middle)
  • Apartments have 90 min doors.

Existing Structure NFPA-101 is used (2012 is the edition adopted by our state)


  • Existing Mercantile: 
    • Requires a fire alarm system only in Class A mercantile occupancies. 
    • Chapter 37 ( (1) ) Class A mercantile is defined as exceeding 30,000 sq ft. 
  • Based on the information above I interpret that a fire alarm system is not required in the mercantiles.
  • Existing Apartments:
    • States a fire alarm system is required only if if building is more than 4 stories in height or with more than 11 dwelling units.
    • Based on the information above I interpret that a fire alarm system is also not required in the apartments.


Based on the information above would you agree a fire alarm system is not required for this building and that it can be removed? Please disregard the insurance company being a stakeholder and the AHJ as that is a separate topic. I can't seem to locate anything about a mixed use building that would require a fire alarm system. Can it be argued that the mercantiles below pose a hazard to the apartments above enforcing a special provision to have a fire alarm system? 

I did check our state building code amendments and no information was in there as well. 


Any help and answers to the questions especially with code references would be greatly appreciated. Thank you in advance! 


Joseph, SET