I’m using this decking on an over the water non-floating dock. What is recomended to leave a gap between boards or no gap. If so how big of a gap?

Hello, thank you for your question. This decking is commonly utilized for dock applications, though, we do recommend per our installation guide and warranty that the material not be applied to a floating sub-structure which is not mechanically fastened frequently and sufficiently to a building and or a code compliant footing. We recommend that this decking be spaced 1/8"-1/4" between boards lengthwise for proper drainage and airflow. For more information please visit https://www.timbertech.com/installation-help -AZEK Customer Care Team.