Spraying foam on the underside of your roof deck creates an unvented or "hot roof" assembly that can improve comfort and energy efficiency. But what about the spray foam thermal barrier? It depends on how your attic is used. A finished vaulted ceiling will have drywall anyway, while an unfinished, unoccupied attic may qualify for alternative protection depending on the product's evaluation. Don't rely on US attic rules, since BC requirements are different. Western Insulation explains attic and cathedral ceiling requirements in our complete 2026 guide. Read it here: https://westerninsulation.ca/spray-foam-thermal-barrier-bc/