I am looking to close a loft and turn it into bedroom.

I live in Illinois and house (built on 2007) has fire sprinkle system and smoke detectors through all the floors. After closing loft there will be none.

  1. Do i have to install sprinkle system in new bedroom?

  2. Do i have to install smoke detector in New bedroom? Can I just use simple battery smoke detectors or do i need to wire it? Current smoke detectors have common line (interconnect)

  3. do I need to add return air duct in this new room?

  4. Is there anything else I should watch for?

Thanks Arek

  • 1
    Have you talked to the contractor who installed the original fire sprinkler system? They're going to be in a far better position to help you out than anyone here will with sprinklering the new bedroom, especially if the system is fully hydraulically calculated as per NFPA 13/13D (vs. using the IRC P2904 prescriptive rules) Commented Jul 14, 2020 at 3:33

2 Answers 2


You will need to have sprinklering run to the new bedroom, and a smoke alarm fitted as well

In order to keep a sprinklered house in compliance with codes that require sprinklering, any rooms that are added on or "carved out" and are not exempt from sprinklers (small bathrooms and closets are exempted from that by NFPA 13D and IRC P2904) must be sprinklered as well. Note that you will need professional help for this, both because most states require a professional license to work on any fire suppression system and, more importantly, many fire sprinkler systems are hydraulically calculated and thus require those rather non-trivial calculations to be rerun any time the system is added on to.

You'll also need an interconnected smoke alarm in the new bedroom; this is an easier problem to solve though, as it's just a matter of running a /3 cable of the appropriate type and gauge from an existing smoke alarm to a box in a suitable place in the new bedroom and tying that cable into the existing smoke alarm circuit, then installing the smoke alarm. (Of course, if you have an alarm panel with system smoke detectors instead, that's a different story, and probably one you're best off talking to the alarm system installers about. It's not impossible to DIY adding a smoke detector to such a system, but you have to be a little more careful to get the right stuff for such a situation.)

The return duct, however, is not essential; some houses get by just fine with a central return point instead of a fully ducted return. You'll probably want a supply register, of course, which will mean a duct run for the new bedroom, though. You'll also want to make sure the loft has a large enough operable window to serve as an emergency escape and rescue opening (aka "means of escape", or an operable window that provides a minimum of 5.7 square feet of clear area when open with a minimum height of 24" and a minimum width of 20" for that clear area).

  • 1
    Good note on the emergency escape+
    – JACK
    Commented Jul 14, 2020 at 15:51

Yes, you need a sprinkler head in the bedroom, a smoke detector outside the entrance to the bedroom (I like one in the bedroom too), and you’ll need a return duct (or relief through-the-wall register) for the heating system.

You’ll also need an egress window of the correct size too.

  • They may not need a return duct, just a supply, it depends on how their house is setup. They'll definitely need the sprinklering, smoke detection, and egress window though! Commented Jul 14, 2020 at 3:36

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