For years, our crew installed vented frieze blocks that featured time-consuming drilled holes and stapled screening to keep out bugs. The theory was good, but in practice, squirrels and birds inevitably punched out the screens as they searched for nesting sites. Then we found a product that solved the problem.
As shown in the drawing, we now use strips of Cor-A-Vent S-400 (www.cor-a-vent.com) nailed to the tops of our frieze blocks. These polypropylene vent strips come in 4-ft. lengths, and you can nail right through them without collapsing them. We nail strips to the top of a 2x that has been ripped to the right depth before we cut the blocks to length. Roof sheathing also can be nailed through the vent strips without crushing them. They leave a nice black shadowline that seems to fit any house style.
Chris Stebbins, Eugene, OR