Raised deck assistance

[jackeeeyyy]

Its the right way. Grooves down provides ventilation where the boards rest on the joists. Grooves up provides traps for water and dirt to lie their promoting the growth of algae etc and actually make it slippier than a smooth surface.

What do you mean by the groves aren't both sides grooved?

 

[morqthana]

I've never spent much time looking at different ones - I thought they were all like this:

 

[John D v2.0]

There are every option to suit every preference. It's personal preference which way to put them, although theories abound about which is the"correct" way.
If there are expansion/shrinkage grooves in the decking then they should be at the bottom, but they are not that common to find.
Personally i prefer smooth but each to the own.
If you do put them groove up, make sure the fall is lengthways to avoid trapping water.