It should be, and will be, but currently it has more gaps round the edges that sealed bits!! I’ve got a tin of crazy foam and some frame sealant to sort it out this weekend.
Really like the simple way you’ve made those osb shelves with battens screwed to the uprights and shelves sitting on top. Think I was overthinking when I made some shelves for my garage when I was routing housings for the shelves to sit in, dust everywhere too!