Not enough insulation depth to stop condensation from forming on the surface of this spray foam roof line. The BER does not recommend installing a flash and batt attic roof installation unless you install enough spray foam to ensure that the surface temperature of the insulation does not drop below the dewpoint temperature of the warm, humid inside air. Also, the surface texture of the insulation will not allow the batt insulation to maintain complete contact with the spray foam, rendering the batt insulation an R-value of close to zero. Not to mention that gravity will eventually pull the insulation down and away from the roof deck in any case. It only takes a small air space to completely devalue the batt insulation. We recommend either spraying the full IECC code required R-value depth in the roof deck, or a flash and net/spray in place fiber or cellulose insulation that is fully supported with rigid backing so it does not sag and separate from the spray foam surface. In any case, the spray foam should be at a sufficient depth to ensure no condensation will form on its own, regardless of what additional insulation you install beneath it.
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