I'm not familiar with plastic baffles and a cold house. Tell us more...
Your choices with a roof are a cold roof, or a hot roof. With a cold roof you have an air space between the underside of the roof and all of the insulation and the hot house.
With a hot roof, you have house, insulation, and the roof right on the insulation, no air space. The issue with that, is even with great insulation, some of the heat of the house will transfer into the roof. With even a little of the house heat transferring into the roof, you will get snow on the roof that melts, starts to slide off, and then at the edges of the roof, where it is colder, the snow will refreeze creating a dam. The dam can then keep melting snow and water from running off the roof. Then the water tries to work itself into any seams or gaps to rot everything. It also makes icicles that can destroy gutters and such.
With a cold roof you have a gap between the roof and insulation to keep the roof cold, so none of that happens.
In a "standard" house with an attic. You are supposed to have all that insulation in the attic floor, and then vents in the roof edges, and the ends, and maybe a ridge vent.
But... he is building a vaulted roof, so trickier...
) have managed to spread out the fill, decently enough. The coop is back up and larger and taller, NO MORE STOOPING TO ENTER!!! And, kid 5 is now putting the fences back up!
