I am getting close to needing to build a ladder for my 10'+ tall book
shelves. I'm probably going to go the less expensive route and simply
build a lean-to ladder. Fancy hardware and wheels and bars and stand
offs would be at least $1,000.00.

Anyway has anyone done this? I am in particular wondering what the
minimum angle should be to prevent falling backwards. I am not going to
attach the ladder to the book cases, my plan is to put rubber feet on
the bottom and maybe felt pads where it will lean against the book case.
I'll just pick it up and move it as needed.

I am certain a normal step ladder ladder is probably a good angle but I
do not want to take up any more floor space than necessary if I leave it
out and leaning against the book case all of the time. Alternatively I
can stand the ladder at the end of the cabinets out of the way.