Have to reattach a 2x12 outside trim board to block wall. Looks like original nails are pulling out. Do I use block anchors, tapcon screws? How do I cover the mounting hardware?

Tell us more about what you are doing, Unusual to see 2x material used as trim.

A 2x12 siunds more like a ledger board. Tell us more

Yes it is a 2x12 board that goes around the house like a band and goes around the lower half of the front windows. Don't know if I should call it a fascia board, it is a real 2x12 board. Thanks

I would use exterior adhesive made for masonry block AND tapcons