Paul Cuenin wrote at 2014-11-13 19:04:14
It really depends on the thickness of the boards you are using as to how much spanning is needed as well. The thicker the board the less spanning required. Here is good installation guide.http://eastteak.com/all-resources/installation-guides/
As long as you install your screws consistently then I wouldn't worry too much about their appearance of course if it is an a issue you can always use plugs. I think 12 inch spanning sounds like a good idea though with the heavy use and the weight of Ipe decking.