Terrace Bankirai outside, what is the distance between the wooden planks?

Learned something new again

I am currently reading up on the topic in more depth. The joint width should be at least 7mm or 6% of the board width. Minimum distance to surrounding components 20mm

But why? All sorts of things fail?!

Of course, you can do less, but it is not sensible. In wet conditions, the water cannot drain properly and dirt remains stuck between the joints. If the substructure is not properly ventilated, the terrace will eventually rot from underneath. The lifespan is greatly reduced. Unfortunately, the joint gaps do not provide sufficient ventilation. For example, additional ventilation should be ensured on the sides.

In case of fear of rotting of the substructure, it can also be made from WPC

Since WPC also has a relatively high wood content, it is not weather-resistant and will eventually rot. The WPC substructure would need to be ventilated in the same way. In addition, there is greater expansion compared to hardwood. It would have to be a WPC mixture that has similar properties to the wooden decking. Personally, I have ruled out WPC as a substructure. It will be either aluminum or hardwood with similar properties to the decking.