Spacing for residential spindles in BC is 4", the top rail has to be 40" high and the bottom one has to be within 4" of the floor. It is supposed to be able to take either 450 or 900# force, I forget which.
I did mine out of 4x4 posts and mortised holes out of the sides to accept 2x4s then screwed 2x2 pickets between the 2x4s on 4" spacing. The mortising was a pain but it looked nice because I just PL Premuimed the 2x4s in. If we had stayed there I would have put another 2x4 along the top to make it stiffer and a place to rest a drink.
Another thing I would recommend to anyone who has a deck or is going to build one is Ducan Dekmaster. It will cost you a bit but you will have a 100% waterproof deck, easy to clean the snow off in the winter, cool to the touch in that Kamloops sun and looks great.
http://www.ducan.com/dm.php
The deck I built/rebuilt in Kamloops had Ducan on top and I was able to build a small shop underneath it.