This week's ATOH episode showed the installation of closed cell insulation in the roof rafters of an attic. I have previously seen this done in other shows, but a baffle was used to space between the roof sheathing and the insulation. I've assumed that is in case there is a roof leak, but this wasn't used on ATOH. Is this baffle not necessary? I'm planning an insulation project and debating on Closed over Open cell (I understand the benefits). But I have a 70 year slate roof and am hesitant to seal the rafters without this baffle. I live in Richmond, VA, a pretty mild climate, so the benefit of Closed cell may not even be necessary. Any advice is appreciated.