Is this so you can fill the depth of the joists and then have a gap above? Which means you can vary the spacing.
Or just batten on top of the existing joists (not 'counter')
I’m probably using terminology wrong here - essentially there’s rockwool type insulation atop the joists at the mo, so will use timber at 90 degrees so the insulation doesn’t get squashed.
No you're right then, if you're laying battens 90deg across the joists. But then you can space them as you like, doesn't have to be the same as the joists spacing.
Is this so you can fill the depth of the joists and then have a gap above? Which means you can vary the spacing.
Or just batten on top of the existing joists (not 'counter')