ᐅ How wide is the solid terrace partition wall?

Hello,

What would you suggest as the ideal width for a solid terrace partition wall?

Our terrace will be 3 meters (10 feet) deep, but we plan to extend it to 4 meters (13 feet) later on.

Should we make the terrace partition wall 4 meters (13 feet) wide as well, or keep it at 3 meters (10 feet)?
What is usually common practice?
Is the terrace partition wall always the same width as the terrace depth?

For a semi-detached house? I would adjust it to the depth of the terrace if the building plan/planning permission allows. Often, only 3 meters (10 feet) depth and 2 meters (6.5 feet) height are permitted.