Is my timber frame outbuilding going to be ok like this???

Hi I'm going to be making a timber frame outbuilding on timber posts. I was wondering if my section drawings are ok. I'm pretty sure the floors fine as air can flow underneath the building and the walls have a breathable membrane so think that's ok but not sure about the roof because it won't be able to breath due to the joist running in different directions to counter lever itself. Any help much appreciated