I made some progress on the baffles to keep the roof deck plywood ventilated and dry above the insulation. While you can buy prefabricated plastic or styrofoam baffles, I recycled scrap wood for almost everything (except the Reflectix, more on that below), so its cheaper, though it will require more labor to install. I got time.
I started at the bird block vents by adding 3/4″ thick vertical spacers and then a 1/4″ plywood baffle for each rafter bay. Besides keeping the insulation from blocking the vents, it will also prevent 60MPH air from driving on the freeway from bunching up the insulation:
For the roof deck part of the baffles, I’m using Reflectix, a radiant heat barrier product made from polyethylene bubble wrap sandwiched between metal foil layers. I bought four 4′ x 10′ rolls and cut them into 16″ wide sections, one for each rafter bay:
Here it is test-fit into place. I’m using plastic capped roofing nails to attach it. The Reflectix will not only keep insulation from impeding the airflow, it will also reflect 97% of the sun’s energy, so the loft should be much cooler in the summer.