Rank: Forum user 
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We have an internal room with no fire alarm sounder. What sound level would need to be reached in this room from another sounder outside of the room for us to comply with fire regulations?
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Rank: Super forum user 
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It needs to be 5dB louder than the ambient noise level. So a sounder outside the room should be fine.
https://www.safelincs.co.uk/a-summary-of-the-bs5839-1-2017/
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Rank: Super forum user 
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Sorry You can’t really ask this question and expect a sensible response. It depends on: - what the room’s walls are made of
- how far the sounder is from the room
- who might be next to the sounder when it goes off- if it is loud enough to penetrate into a room it might well causes hearing damage to someone working next to it if it goes off
- The frequency of the sounder might be an issue as different frequencies penetrate at different rates
- Etc
If you really want people to hear the sounder and for it to be clear and unambiguous that this alarm is meant for them you need a sounder (or flashing beacon) on that room.
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Rank: Forum user
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The information you need may be found in BS5839, excerpts from which can be found on various manufacturer/installers websites. (Search “Fire alarm audibility requirements”) It appears 65dB(A) is the norm or 5dB above background in noisy areas but not more than 120 dB for hearing protection reasons. My search was limited to the UK and it also turned up a Forum discussion from 2006
http://forum.iosh.co.uk/posts/t71971-Minimum-Level-For-Fire-Alarm-Sounders
In sleeping accommodation, it should be a minimum of 75dB(A) at the bedhead. If the sounder is just outside the door, then as a rule of thumb, an internal door will reduce the noise by 20 dB, a heavy fire door by as much as 30 dB. If the alarm noise level outside the room is not at least 85 dB then the alarm noise level in the room may not be sufficient. So an additional sounder or visual indicator in the room to alert the occupants (or other means of raising the alarm) would be required. Bottom line is that the alarm must be recognisable throughout the building, taking into account ambient noise levels, hearing impairment of occupants, sleeping accommodation etc etc etc Hope this helps.
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Rank: Forum user
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Thanks for the information.
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