I stapled chicken wire around my 48 foot long deck - it was fairly inexpensive. I went from underneath to the top of the second horizontal rail. I was afraid my Mr.Darcy would drop between the deck floor and the first rail where there is a 5 inch gap. He jumped off the counter the other day when I was grooming him - he was gone in a split second- under my arm, and cried and almost growled when he first landed - scared the heck out of me as I know someone whose toy poodle did that and broke both her front legs...
now I am hoping it scared him too, and he won't try a leap like that ever again!