Smoke detector location


Active Member
This is for a home [still] under construction. It's time to do the rough-in wiring for smoke detectors, so I'm trying to determine locations for smoke detectors. I understand the general rules, i.e., every sleeping area, hallways outside sleeping areas, three feet from HVAC supplies and return airs, etc.

The attached file is a drawing of the area around the master bedroom entry door. My question is about the area shown as the "master vestibule. It's essentially a small hallway (about 8' x 4', 10' ceiling height) connecting the family room to the master bedroom and utility/laundry room. I will have a ceiling mounted detector in the master bedroom located about 18" inside the bedroom door.

I think the guidelines say I need a detector in the vestibule (because it is a "hallway leading to a bedroom"), but I don't see how it will do much good. The drawing doesn't show it, but there is a ceiling mounted light in the middle of the vestibule. If I follow the 3' rule, it looks like the only place I could put one in the vestibule is "past" the bedroom door.

Is the assumption that if a fire starts on the vestibule side of the master bedroom door (including in the family room and other rooms not shown), the top couple of feet of the vestibule may fill with smoke and set off the vestibule's detector before the smoke reaches the master bedroom? Seems like that isn't a good bet given the location of the return air.

The house is located in the county, i.e., outside the city limits, so there isn't any inspection done on issues like this.


  • South side.pdf
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If you place one anywhere near your kitchen you may need to get a visible smoke unit as the ionised air ones will go off everytime you turn on a gas burner or push the toaster down. They don't trigger on visible smoke but the ionisation of the air from the flames or heat.
Thanks for the tip, but I'm really just asking about the locations in the previously attached drawing. That location is nowhere near the kitchen.
A lot of people close their bedroom door at night. This might be for security, fire protection, or because they don't want to hear the load of clothes running in the washer. If for example a fire starts in the dryer at night and the door is closed, a detector in the vestibule will give an early warning to enable the inhabitants in the master bedroom to escape.