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2010 CBC S2 & F2 Fire Seperation Question

2010 CBC S2 & F2 Fire Seperation Question

New postby Charlesm on Wed Feb 08, 2012 1:05 pm

This has come up twice recently and I have yet to find any reason for it.

We have a building of V-B construction going in that has a small retail(M), office(B), and storage(S2) totalling just under 2000 square feet. The office and storage are too large to be counted as an accessory use in this case. The storage fits best as an S2 due to it being very low hazard items. What is confusing here is that the code, in table 508.4, requires an S2 Low Hazard to have a 2 hour seperation from a B or M occupancy. However, the S1 Moderate Hazard does not require any seperation from those same occupancies. I have talked with other people and nobody has any idea why this is. I have read everything I can find in the code that could possibly be related to this seperation requirement and table. There are no footnotes or exception listed.

To make this a little more confusing, I also found that this is exactly the same for an F1 and F2 occupancy. You can take the paragraph I typed above and replace the S1 and S2 classification with F1 and F2 and it would still be the same question.

Any help you can give to explain this would be greatly appreciated.
Charlesm
 
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Re: 2010 CBC S2 & F2 Fire Seperation Question

New postby Jerry Peck - Codeman on Wed Feb 08, 2012 10:14 pm

Charlesm wrote:What is confusing here is that the code, in table 508.4, requires an S2 Low Hazard to have a 2 hour seperation from a B or M occupancy. However, the S1 Moderate Hazard does not require any seperation from those same occupancies. I have talked with other people and nobody has any idea why this is. I have read everything I can find in the code that could possibly be related to this seperation requirement and table. There are no footnotes or exception listed.


I wish I could explain it - I have done the same as you and achieved the same results ... "and nobody has any idea why this is".

Any help you can give to explain this would be greatly appreciated.


I suspect that this is a carry over from older code editions where the fire-resistance requirements of the different occupancies was specified, and the listed occupancies had the same or similar fire-resistance requirements, which means no separation would be required between occupancies with the same or similar fire-resistance requirements. Given that S-2 would have had lower fire-resistance requirements due to the lower hazard, S-2 would have required increased separation from from the other occupancies. At least that is my best reasoning to date.

Other than the above, I really don't have the answer to that table, and neither has anyone I have talked with. I suspect that table is something which will be undergoing some changes in future code editions, and if it is changed, hopefully the intent and reason for what appear to be inconsistencies will be given or made known.
Jerry Peck - CodeMan
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Re: 2010 CBC S2 & F2 Fire Seperation Question

New postby Charlesm on Thu Feb 09, 2012 12:52 pm

I appreciate you looking at this for me. The hunt will continue and if I manage to get any further explanation I will post it here.

Thanks
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