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Wall / opening ratings between adjacent dwellings?

Yikes

SAWHORSE
Joined
Nov 2, 2009
Messages
4,022
Location
Southern California
See image below:
1707268428895.png
Assume all structures are type V-B, and are collectively small enough to be treated as a single building on the same lot (503.1.2).
What are the rating requirements for walls and openings:
  • Scenario 1: Dwelling Units A and B have a one hour fire partition between them (pink highlight) for dwelling unit separation per 420.2. The exterior wall modulates to create an alcove, and the alcove has unprotected operable windows in each unit (yellow highlight) that directly face the other unit. What separation, if any is needed between the windows? Assume they are not EEROs.
  • Scenario 2: Dwelling units C and D are completely separate, but very close to each other. They are no longer "in the same building", but 503.1.2 allows us to treat it as one building. Do the two exterior walls close to each other need to be fire partitions per 420.2? do the yellow windows need protection? If "yes", then how far from each other must they be located to eliminate protection requirements?
 
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