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Is house wrap needed when using exterior insulation and a different rainscreen?

 
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Hi All,
I can see the benefit of house wrap when you have the sheathing -> house wrap -> siding. However, I intend to renovate a wall where I was thinking of doing sheathing -> 2" rockwool -> rainscreen/airvent -> siding.

Both companies of the rockwool insulation and the rainscreen both recommend housewrap... but I feel like it's rather redundant given the other layers. Is it really going to help anything?
 
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The purpose of house wrap is to be vapor-permeable, while also being liquid-impermeable. This reduces the risk of moisture buildup on the sheathing.
Rockwool is vapor-permeable, but last I checked it isn't rated to be liquid-impermeable, which means building code inspections won't approve it.
Practically speaking, I saw someone soak a scrap of rockwool in water and it didn't absorb anything in about an hour and water just ran off it.
I think the best building-science case for house wrap is to protect the sheathing in case the rockwool somehow fails.
Beyond that, the building code requirement may be the most compelling reason for house wrap.

Rockwool has the advantage of not tearing easily like house wrap. Rockwool won't irritate skin like fiberglass, off-gas like foam, or settle over time like cellulose. It also gives you continuous insulation, which seems to be way better than the equivalent cavity insulation.
 
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House wrap is water barrier and AIR barrier. Yes, you need something between the sheathing and rain screen, it can be either side of the Rockwool depending on which wrap and the construction of the rest of the wall assembly, but next to the sheathing is normal.

If you are buying osb sheathing I would go with zip or similar. The built in barrier layer uses less plastic and is much more resilient to construction damage and weather if you have a slow build timeline.
 
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