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Proper use of CBC/IBC table 508.4

Joe.B

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Dec 4, 2020
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103
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Arcata Ca
This table has the same occupancy types listed across the top and down the sides and for the most part makes sense. I'm confused about the discrepancies when you get to H occupancies. If I go down to H-3/H-4 then over to H-1 a 1 hour separation is required if the building is sprinklered. If I go over to H-3/H-4 then down to H-1 it's NP, not-permitted. If I go down to H-5 then over to H-2 then no fire rating required if it's sprinklered. Over to H-5 then down to H-2 1-hour rating is required. Do you always go over first, then down? Does this imply, for example, that if you are designing or working on an H-2 (sprinklered) with an H-5 next door then no separation required on your side. If you are on an H-5 (sprinklered) job with an H-2 next door then you are required to do a 1-hour wall? Thanks!
 

Joe.B

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Dec 4, 2020
Messages
103
Location
Arcata Ca
Actually, go whichever way you get a value. If you use it and get a "—," then you used it the wrong way.
That's what I thought it should be. It turns out CA decided a simple chart wouldn't be good enough, they had to throw a wrench in it.

So anybody from California want to take a stab at this? Down then over, or over then down?
 

cda

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Oct 19, 2009
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Basement
That's what I thought it should be. It turns out CA decided a simple chart wouldn't be good enough, they had to throw a wrench in it.

So anybody from California want to take a stab at this? Down then over, or over then down?

Cannot copy and paste it

but this table 508.4????



I like go down first than over ??

Are we missing something ???
 

Joe.B

Registered User
Joined
Dec 4, 2020
Messages
103
Location
Arcata Ca
The link you provided is what I'm looking at. Down first then over appears to be the less restrictive approach, which is what has me worried. Generally when there are conflicts the "more restrictive provisions shall apply". I was wondering if anybody else has had this come up in review. I see two possible interpretations: Go with more restrictive = go over then down in all cases. Or top row is occupancy in question (review/approval), side column is adjacent occupancy. Thanks for taking the time to consider this apparent conflict.
 
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