This may be a dumb question so I'll apologize ahead of time...

I'm having trouble creating physics for buildings with stairs. I'm creating the phys from the mesh because any other format will not allow complete access to the building. I'm finding that the player can't walk on or climb the stairs. Is there a way to manipulate the physics to allow walking up the stairs or will I need to create a climbing animation for it?

why can't he walk on the stairs?
maybe the steps are too big (too high)?
phys from mesh is good choice for stairs, so it should work ok, unless you have some other obstacles there.

In my experience, the steps themselves are too big for the avatar physics box to manage. Try using a 'helper' prim, in the form of a 100% transparent ramp. Also check you don't have gravity setting too high, -9.8 is 'normal' albeit I often set it to -15, so you don't have an arc glide, down stairs/slopes.

You can create the physics hull manually. you can do this in the mesh editor by moving and scaling primitives, but I choose to do it in my modelling program since it makes it so much easier. Just create a simplified version of your model on top of your existing one, select it, and export selected as whatever you exported your original model in. Now, you have your .mesh for your building, import the simplified mesh in the mesh editor, create physics from shape and there you go. Now save this .phys with the same name as your original building.

If that didn't answer your question, I had trouble with stairs as well. I ended up using concave to make it a flat surface. Make sure the step-size is small enough like said above.

Try scaling down the size of the building and see if you can then walk up/down them. If you can, then the stairs are just too big, so try tweaking them a bit or try one of the other techniques suggested above. My game had stairs in it and it worked okay (other than the fact that if you stood still on them, you would slowly slide down all the way to the bottom). Just have to make sure they're the right size.

As mentioned in the above posts, you could make the stairs smaller and therefore more steps. If however you are going for a more real/natural look/feel to the build, then making the steps smaller may not fit in with what would be naturally perceived by the user. I find this a lot when I recreate existing buildings etc. In addition, when the user climbs the stairs, you may find the screen jumping up and down (juddering) making the scene uncomfortable.

Your only real alternative would be the ramp helper prim.

Great, thanks for all of the suggestions and help. I'll play with it and see what works best. I think the problem is that the stairs are just too big, even when scaled down (then they also become disproportionate to the player). I see others have come across the same issue so now I don't feel like I was missing something. Thanks again.