TOPIC: Shims under beam ends

I've had this question come up once or twice a year, and I keep forgetting to research it. Now, in the last month, I have had 5-6 newer homes with everything from 2x4 blocking set on end to PVC trim being used as shims under wood and steel beams alike.

I know there are clearances required for wood beams in the foundation pockets, so are wood shims allowed in any situation?  Wouldn't wood shims crush/creep over time?  When the shims are obviously incorrect I always recommend steel for every type of beam. Am I being nit-picky?

Thanks for any response.

Cameron:

Specifications will vary depending on the authority having jurisdiction. However the best practice is always steel under steel, and wood of the same species under wood beams and always full bearing at the wood member/shim contact point. Multiple shims should be perpendicular to each other. Multiple shims should also be glued together. You are not being nit-picky. I recently had an inspection where the beam had rotated on the masonry pier because of poor shim installation.