Using Intello for Retrofitting failed spray foamed wall from the outside – GreenBuildingAdvisor

Exterior 2×6 wall on post and beam frame has wet plywood and framing in places.  Probably many problems with initial design.

From inside out: sheetrock, 2×6 cavity with 2.5″ closed cell spray foam (at exterior side) sprayed onto: 1″ styrofoam board, 5/8 plywood, tyvek, cedar clapboards.

So foam inside and out and clapboards tight to plywood.

I believe humid inside air was getting into the top of this wall where spray foam didn’t always reach, and causing moisture damage to wood.

Looking to save the wall.  Current thinking is to remove all foam, replace any wet or damaged 2 X 6s, create this wall:

sheetrock, **Intello smart vapor retarder **,  2×6 cavity with 5.5″ mineral wool batts, 5/8 plywood, Hydrogap SA WRB, 2″ mineral wool board, 1 x 4 strapping creating rainscreen with vents, composite clapboards.

** My question is about the Intello.  We only have access to the wall from the outside.  When we remove all foam and repair bad 2x6s, we will see the outside surface of the sheetrock behind the now empty 2 x 6 24″ o.c. frame.

We could then install Intello, sealed at top and bottom plates and taped at Intello joints.  However this means both the sheetrock and the 2X6 will be inside the Intello as we cant get it under the 2X6s.  Do we trap moisture in the 2x6s this way?

More time consuming – We could maybe cut and seal the Intello in each bay so with a lot more effort we could cover the sheetrock but not the 2×6 (in this case there wouldn’t be any intello inside the 2x6s so vapor would still travel to them).

Any suggestions for the best solution, or alternative ideas.

Thanks!  Jeff in NH.