Great information given already. As you know, I installed a pond next to my deck. The deck is only 18 inches off the ground but we had spindles and rails put in for safety. We did remove the rails and spindles for the pond on one side but we kept them in case we sell and the "code" is to have them up. Right now the flower boxes are screwed to the deck to avoid Jim's wheelchair from going into the pond. I kept it in the back of my head that I may need those rails again. lol We had a permit when we built the deck and no one questioned our drawings so I guess we're good.

If you look at my pond thread you'll see how our spindles and rails are built into the deck. I think the spindles about 3 inches apart each and the rails maybe 3 foot apart. I also have a ramp built into the deck with bumpers on the bottom.