Deck board spacing
 

How much spacing should I have between decking boards? I'm using 5/4x6 pressure-treated wood

If your wood is new/fresh, still moist, then press the boards as tight together as possible. When they dry out completely, you will have a nice uniform space between them.
If your wood is already fully dry, then leave 1/8th of an inch between them. Use a nail as a spacer to keep them uniform in space.