In an unsinsulated service cavity (created by running horizontal 2x lumber) is fire blocking required? Or is it a good idea?
My proposed wall assembly from outside to inside:
1. Ribbed steel siding
2. 3/6″ fanfold battens to create air space
3. 1/2″ cdx
4. 2×8 stud cavity filled with wet spray cellulose
5. 2″ eps nailed to studs (interior uninterrupted rigid foam)
6. 1.5″ uninsulated service cavity (created with horizontal 2x4s)
7. 3/8″ acx plywood (interior wall finish)
The building is a heated workshop with some pretty high electrical needs for the machinery. Since it’s not a residence, I could probably forgo the fire blocking. Leaving an open horizontal service cavity would allow for easy electrical changes in the future.
If the consensus is that the fire blocking is a good idea, I would probably fill the service cavity with blown insulation.
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