Use cold floor as storage space?

We have also now, after 2 years, laid tongue and groove boards on the middle area of the (hip) attic floor. The floorboards have minimal gaps and are only fastened at one end, so that everything underneath can move freely as it pleases.

Best regards, Gabriele

Is there currently no covering on the beams at all, meaning the story up to under the ridge is open?

No, it looks exactly the same for me as it does for

Then do it like Nordlys and screw tongue and groove boards onto it and save yourself the counter battens nonsense.