What is the best material and sealer to insulate a cold storage that is against an outside wall. Hope to hear from you soon.
For a "cold room," typically under a porch, use at least 2 inches of XPS tightly sealed. In Ontario, you don't have to provide further coverage. (At least, that's how the inspectors in TO have interpreted the OBC.) This should prevent condensation. You should also use a well sealed exterior door and provide venting. If this is actually a year-round refrigerated room, it's a different story.