BATTENS FOR ROUND BAYS
Note, you might not need to use battens as there are three alternatives:
1. You can use D1 fixings
2. You could swap your handles for a low profile design
3. You could use Bay posts.
You can use battens to space the shutter frame away from protruding objects and to connect the corners together when fitting shutters to a round bay. Deeper battens such as 40mm will be better on round bay windows as larger height deductions are required to allow the frame to fit properly. More is deducted from the height as bays can be out of level and all the shutter frames need to be connected together, so what happens one end of the bay will affect the other side too when you make any adjustments.