I need to verify the species and grade of existing roof joists. Any ideas on how to go about this? None of the local testing in my area are able to help.
The surest way is to cut a coupon sample of the joist and send it in a zip-loc bag to the Forest Products Lab in Madison, WI. They can tell you the species. As far as grade, I would pick the stresses for either "Construction Grade" or "#2 and better", which is what most lumberyards carry for structural lumber. Higher grades are usually special order.
I assume SPF #1/#2 when I don't know otherwise. It has relatively low (and therefore conservative) values.
It is interesting to look at older NDS Specifications--lumber properties (such as Fb) have actually DECREASED over the years (I think due to using faster growing trees these days).