Interconnecting smokes

[mdshunk]

To anyone who has access to NFPA 72

Does this code (likely section 5.5.2) require that the smoke detectors in a multi unit building be interconnects within each dwelling unit, or between all dwelling units in the building? Would it make a difference if the dwelling units had fire walls in between (like as townhouses are constructed)? Would it make a difference if it were an old multi-floor walk up without fire walls, like many downtown apartment houses? I realize that the local rules and the local fire marshall prevail, bla, bla, bla. I just wondered if NFPA 72 had anything to say on the matter.

[Wgoodrich]

If you have a 4 hour fire wall floor to roof decking then each fire wall makes a new separate building with its own contained fire protection interconnected within those fire wall areas as different buildings even though attached.

If no fire walls then entire building is interconnected.

If community hallways those community hallways are treated as a part of the same dwellings interconnected without fire walls but as a separated building with fire walls as discribed above.

Fire walls and building fire rating makes all the difference in the world when dealing with fire protection.

Most often apartments of 3 or more have fire marshal rate the building fire rating and declare where and rating of fire walls.

Fire protection is governed by NFP 72 and building Codes not NFP70/NEC

By electrical concerns NFP70 a 1 hour fire wall makes a separated building but a separated building per building codes and NFP72 are more stringent as discribed above.

See you local rules before you commit.

Good Luck

Wg

[mdshunk]

Thanks for that reply. In my mind it boils down to the time period in which the multi-unit building was constructed. I think that it is fairly safe to say that if a building is old enough to need completely rewired (what I usually am doing), then the building likely does not have the requisite fire rating between units for the "seperate dwelling" ruling. In this case, the whole building would need interconnected smokes. That somewhat confirms my gut feeling, but I never read any actual text on the matter. The information on the net is somewhat sparse regarding multi-unit rennovation. When you go into more than two units, you're in a whole new ballgame.

[Ron]

I have NFPA 72-2002 in front of me. 5.5.2 is detector coverage.
BTW, I found many requirements for smoke detectors in the applicable building code too (of which I don't have handy).
Would your building be considered an apartment building? 11.5.3 is titled "new apartment buildings" and 11.5.4 is titled "existing apartment buildings".
They indicate that notification should be within the dwelling unit only, not the whole building. Although I would interpret a hallway smoke sensor to activate notification in common areas, not the particular dwelling unit, but residential is outside my area of work.

[mdshunk]

Would your building be considered an apartment building? 11.5.3 is titled "new apartment buildings" and 11.5.4 is titled "existing apartment buildings".
They indicate that notification should be within the dwelling unit only, not the whole building. Although I would interpret a hallway smoke sensor to activate notification in common areas, not the particular dwelling unit, but residential is outside my area of work.


Now I'm confused, but that's okay. Yes, the building would be an apartment building and it is existing.

[Wgoodrich]

Existing or new it all depends on separated buildings by fire rated walls. You are correct many older apartments or converted doubles from single family dwellings have no fire separation. This would require whole building interconnected. All depends on fire separations not normally found in older buildings. You are not the only one confused. This subject has many local interventions in form of ammendments to those rules by local yokals that add to the confusion just for added challenge to you.

Good Luck

Wg