Insulation, Radiant and Vapor Barriers - What type of material for soffit baffles

I am planning on blowing in insulation in the attic. I have purchased some plastic soffit baffles from Home Depot. After purchasing them I found out that they are 14" and are stapled to the roof sheathing. I would rather make my own type of baffle and attach to the attic side of the rafter. I have about 20 vents cut into the soffit which occupy two rafters. So I am trying to make a baffle that would cover both rafters about 34" wide. What material would be safe to use to make soffit baffle. Thanks in advance.

There are three objectives for soffit baffles. 1. To allow cold air into the attic to keep the bottom of the roof deck cold. Helps prevents condensation and snow melt resulting in ice dams. 2. Properly positioned, they prevent the blown in insulation from blocking the soffit vents themselves. and 3. By building a baffle down over the end of the insulation, you can reduce the wind washing effect, where air movement through the end of the insulation reduces it's effectiveness.

You mention two rafter bays per vent. You should actually have baffles to protect air flow for all rafter bays. If you choose to install a baffle along the attic side of the rafters, you will have ample venting space above, but, depending upon how your rafters and joists are installed, may be limiting the insulation over the top of the wall. The top of the wall is usually a cold spot and needs all of the help it can get.

As for material, if permitted, I have seen the 1/2" foil faced rigid foam fitted as needed.

Bud