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Necessary to insulate space between sprayfoam in rafters and ceiling paneling?

dfvellone | Posted in General Questions on

I’ve had the 5′ slopes of my rafters in my cape insulated with sprayfoam and am ready to install the finished ceiling. There’ll be an inch on average of space between the sprayfoam and the backside of the finished ceiling. Beyond additional r-value, is it necessary to fill that void? 
Thanks, Daniel

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  1. Expert Member
    Akos | | #1

    Air gaps on the warm side of insulation are never an issues. The problem with gaps is only on the cold side where it can create convective loops.

    There is very little assembly R value benefit to adding insulation there, even if you are going to DIY it, it is not worth the effort.

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