This is one of thoseobvious things that I should have thought of a lot sooner. Our woodstore is on the back of the cottage with a door that allows you to get in from inside the house. It has slatted walls to let air circulate, but its always had a solid roof because we used it to get up onto the green roof above. Having seen a woodstore with a clear roof, I realised that we were missing out.
What a revelation. Now the sun can dry the wood better, and we can get around the woodstore without bumping into things in the dark. Such a simple change, but such a huge improvement, and still enough solid roof to get up onto the green roof.