Could anyone let me know whether bitumen waterproofer will be good for waterproofing osb sheets.i dont really want to cover the sheets with roofing felt as i was told it can easily get torn .please advise me.thanks. Making shed water proof. by james also i do tend to sheath the walls (beyond the floor level and the rim joists)and roof structure with osb 3 / wbp plywood, thereafter i will attach a vapour barrier fabric before cladding with lap, shiplap or tgv. waterproofing your shed by: john shank. Best way to weatherproof osb. ask question if you want to use osb to sheathe the walls of your shed, you need to build those walls like the walls of a house: with a weather-resistant barrier like tyvek over the osb, and then cover that with siding of some sort. vinyl siding is cheap and diy-friendly..
