What is the thickness of a fire-rated duct? A fire-rated duct needs to be made with just one pores and skin, using a whole thickness not exceeding 2mm. This measurement contains the intumescent coating, that is important for boosting fire resistance. In accordance with the World Overall health Organisation (WHO), https://fire-resisting-ductwork46788.blogdanica.com/39511496/new-step-by-step-map-for-fire-resistant-ductwork-manufacturers