Thur ya go, Chingy.I know a person on 30A with a spray foam rafter house. Was great r-value, but just like above post said, a leak developed, probably 10 years back, foam hid leak, trapped it, and let it spread over a huge area. Now rafters, sheathing, foam, and roof need to be replaced. Oh requires mold remediation now. Big $! Open cell foam and moisture are not a good combo. Fortunately he has cinder block for exterior walls but moisture worked it's way down the interior of 3 floors. Good thing his pockets are deep and it's his "little" 5000 sq ft summer, beach home.
I understand that he wants to insulate airspace between battens. Waste of time, money and a bad idea.
And closed cell foam and moisture don't make a good combo either. Trapped moisture is never a good thing. See my above comment on EFIS.
I got a good mold remediator.
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