Maintaining the proper baluster spacing on your deck railing system is important for both aesthetics and safety. Most building codes require a maximum space less than 4" between baluster edges. To be safe, I recommend spacing wood
, glass and metal balusters
3.75" apart (edge-to-edge).
For aesthetics, keep the on-center baluster spacing approximately the same around the perimeter of the deck.
When marking for baluster placement, start in the middle of the railing section and allow small space fluctuations to fall near the pressure treated wood or composite lumber posts. Note: drill pilot holes before driving screws into rails to help eliminate splitting.
Check out this tool
for a quick and simple way to determine how many balusters your deck railing will need.
Also important to note, there needs to be a gap less than 4" between the lowest point of the bottom rail and the composite lumber or treated wood deck surface, although I would recommend a smaller 3" gap, as it looks better.
Check local building codes in your area for specific details.