In general terms, joists spaced 16 inches on center can span 1.5 times in feet their depth in inches. A 2x8 up to 12 feet; 2x10 to 15 feet and 2x12 to 18 feet. The larger the deck, the larger the joists.
Similarly one may ask, what is the gap between decking boards?
Overall, conventional decking profiles should be installed such that when seasoned, will have gaps between 1/8 and 1/4 of an inch. Look at the ends of the boards and install the decking "barkside" up to prevent cupping. Install decking with 3" pressure treated compatible deck screws instead of nails.
How far apart are posts for a deck?
In general, posts should be spaced no more than 8 feet apart. Some builders position them every 4 feet for a completely rigid frame. The maximum distance between footings is determined by the size of your joist material.
Which side of deck board goes down?
The debate about whether deck boards should be placed "Bark Side Up" (growth rings curving down) or "Bark Side Down" (growth rings curving up) has raged for years. Bottom Line: The hype that "bark side up" is always the answer is not accurate.