As you walk up into my attic, I want to create a knee wall that will act as a railing. I have a couple of questions about the construction of this. Is there a certain heighth that it needs to be? I was going to check out some railings and a home improvement store to compare. Also, I've read some posts about anchoring the posts to the floor joists for better stability. My problem is that the floor joists will run parallel with the wall, so I may in the middle of two joists. Is there any way that I can give the wall stability?