When this happens, you roll your contest for Forcing (DF2, p. 8) vs. the higher of the HP of the lock/hinge or bar/wedge with a penalty equal to the higher DR of the lock/hinge or bar/wedge. At least the way I do forcing rolls, it's effectively rolling against DR+HP - plus it's an easy way to visualize something like roll at -3 vs. 14 or roll at -24 vs. 46 as one number.
In any case, you only really benefit from a bar or wedge if the door's DR and/or HP is lower than that of the bar/wedge.
I totally wasted a huge amount of time on this, so hopefully it helps someone. I'll probably use this to make some simplified bar bonuses. I didn't really feel like hand-coding such a long table so I let Blogger do it - hopefully it's readable. It's a look at combos of doors and bars, and the total of higher DR + higher HP.
|Hinge||Bar||Better DR||Better HP||Total bDR+bHP||No Bar DR+HP|
I bolded the ones that make sense as combinations - the weaker bars and wedges just don't help really strong hinges/locks. And vault-grade bars don't help vaults, actually. Only 15 out of the 25 combinations make any sense. Don't stick a rubber door stop into a vault and think it'll make it harder to open.