[wejones]

While I agree that it makes alignment MUCH MUCH easier, it isn't necessary that the pole be plumb. There used to be a fellow on the web who had demonstrated how to align a polar mount on a pole that was sloping something like 40 deg. I didn't beleive it at the time, so I made a little wooden model of a dish on a polar mount intending to prove that it wasn't possible, but I ended up proving that it WAS possible. A non-plumb pole sure makes it hard, however, so it's highly recommended to make sure that the pole is plumb. Re the slope of the roof, I think that would only affect how high the pole needed to be, so as not to bump into the roof.