Interpretation #7711
Published January 19, 2016
Original Request
- Code Version
- 2014
- Code
- BUILDING
- Code Description
- Chapter
- Section
- 907.3.1
- Topic
- Smoke detectors in supply and return
Question
Are duct mounted smoke detectors required in both supply and return air ducts in units with 2000 cfm and above?
Answer Published 01/19/2016 at 2:34 PM
This item went before the FBC in the Fall of 2015, the
commission stated that there was "not a conflict" between
the building and fire codes. That leaves the interpretation
up to the local AHJ. Building requires it in the return and
fire requires it in the supply........ So, if there is no
conflict..... it is required on both sides.
commission stated that there was "not a conflict" between
the building and fire codes. That leaves the interpretation
up to the local AHJ. Building requires it in the return and
fire requires it in the supply........ So, if there is no
conflict..... it is required on both sides.
Commentary
It should be noted that FBC Code does not reference NFPA
90A, but NFPA 90A still requires smoke detectors in the
supply. FBC diverges from NFPA 90A because the
International Code now also diverges. Both the International
Code and the FBC require smoke detectors in
the return.
The Building Departments generally require compliance with
FBC and the Fire Departments usually require compliance with
NFPA 90A, so as a practical matter there are two detectors
required, one in the supply and one in the return. This is
true, even though analysis of unreferenced NFPA 90A is (now)
beyond the scope of this forum.
One detector (The one in the return) gives "earliest
warning" of a fire in the space; the one in the
supply heralds a fire in the air handling unit or fan.
Bottom Line, put 'em both in.