Hi folks,
I like the concepts of borate rods, although you'd need a lot of them. So long as you can keep access to inspect the holes periodically to see if the rods are being dissolved.
I'm a long way away, but our city building code (which follows UBC and IRC, pretty much standards) allows for pressure treated OR rot resistant species. Seems like a person could always put a 2X plate down below your sill of some exotic, such as Alaska yellow cedar, purpleheart, apatong, etc.
Many of these woods easily surpass PT in their longevity.
We have a great building department, and it seems like if you can make a very sound argument for deviating or improving upon code you can get the signature in red ink. Maybe you'd be as lucky...
All the best,
Zach
