Hi Bobby, I use a cover and don't have any issues with mould. I don't crack open the windows. Prior to putting it away I aerate the poptop by leaving it up to make sure the canvas is dry. When closing the lid open the door and make sure all the canvas is tucked inside the van to avoid it getting damp and going mouldy by touching the outer roof.. All the doors and cupboard doors are left open, make sure all the floor vents are clear. I have always used two damp traps, my cover is bespoke with a door, and on a dry day I will open the Eriba door and let the air circulate for a few hours.