The plastic or styrofoam ventilation channels (or baffles) are added after the house is built. They're basically just 3' long 14" wide channels that carry the air from the soffit to the ridge vent. They get installed between the roof trusses (joists) with a staple gun. Very...Very Easy. Took about 2 hours to install all the baffles and another 3 hours to insulate over the baffles.
Here's a great little youtube video showing the entire process. Shoot me a PM if you have any questions.
http://www.youtube.com/watch?v=5DX25Vz2jDc
Here's a great little youtube video showing the entire process. Shoot me a PM if you have any questions.
http://www.youtube.com/watch?v=5DX25Vz2jDc