I'm replacing a deck. Its goes out 12' from the house and 24' along it. Should the outside joists be doubled? (2 boards side by side) I'm using 2x10's for the joists. 2x8's are right on the edge for a 12 foot span. Doubling the joists will make the railing posts sturdier, although I plan on adding some blocking or Simspon brackets to make the posts stronger anyway.
Another question: should I use 2x10's or would 2x8's suffice for the joists?