This is a tricky detail to say the least; it is one that we have to navigate often in narrow-lot, or "zero-lot-line" houses, and with duplex configurations.
First, I would point to the Gypsum Association Manuals that offer tested, accepted assemblies for all fire and acoustic situations - it is the Bible of fire assemblies. Here is a link:
https://law.resource.org/pub/us/code/bsc.ca.gov/sibr/org.gypsum.GA-600-09.pdf They're also available to call to review and discuss - take them up on it. Do not recreate these, rather cut and paste them into your sets so you don't miss anything; the small aspects of the details are what will make/break the assembly and leave you in a difficult position so far as liability is concerned.
Secondly, and most importantly, the execution of this detail in the field by the Contractor, is critical. The sequencing of the layers is often atypical to standard construction processes; it requires trades engage at intervals which a lesser experienced crew will potentially miss. Likewise, inspectors without experience in these assemblies may have difficulty reviewing in the field. The result is often frustration by Contractors - that will likely be taken out on the professional as "something that cannot be built" - just beware. You will likely want to have a pre-construction meeting to walk through these so that they are understood and anticipated. Ensure they have read and understand the assembly in all its details and ensure them that no part can be omitted.
Hope that helps?
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Craig Hausman AIA
Principal
hausman* architecture, inc
Sacramento CA
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Original Message:
Sent: 08-24-2020 18:20
From: Sandy Liu
Subject: Type V: When a fire-rated wall meets fire-rated floor, and vice versa
How do I find a set of details (preferably UL listed or ESR rated, if possible) that solve the intersection between a 1-hour rated wall and a 1-hour rated floor assembly, in Type V construction?
I'm working on a couple of residential duplexes. In each duplex, I have two units that start out side by side on the ground level, then on the second floor, one of the units goes over part of the other unit. The plan checker is insisting that a rated wall cannot end at a rated floor (as in a T-intersection, if viewed in section), that a rated floor cannot end at a rated wall (as a T-intersection if viewed in section), and that a rated wall and rated floor cannot form an L-intersection (if viewed in section). The plan checker says the 1-hour separation wall must extend from foundation to roof. Previous similar projects were permitted, so now I am confused. Have I learned this incorrectly?
Thanks in advance for your advice and guidance!
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Sandy Liu AIA
Pasadena CA
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