The baffles stop outside air (from vents) from infiltration the edge of the insulation over the outside wall/ceiling line. Many people read baffles, and stop there, without adding the Windblockers. Older houses seldom installed blocking under the knee wall, as now required for fire code. That joint is very important to stop air infiltrating: http://www.homeenergy.org/archive/he...95/950309.html http://www.simplesavings.coop/simple...ee%20walls.pdf
Yet, isn't there a warmed room below?
The best way (without spray foam) is: http://www.homeenergy.org/archive/he...96/961110.html
Another reason to block air from the insulation: http://www.homeenergy.org/archive/he...92/920510.html
On the sloped ceiling, add rigid XPS boards, then drywall to get your assembly required R-value there. http://www.coloradoenergy.org/procor...f/r-values.htm
No thermal bridging of the roof rafters.
Just be sure to air seal and maybe vapor barrier--- almost as important as insulation and ventilation.
Be safe, Gary
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!