Wherever the ductwork leaves the compartment from which it serves (shown in blue) it should retain integrity and insulation fire rankings for a similar stretch of time as being the compartment by which it passes. The structural style and design of grease ducts performs a vital part in professional kitchen https://greasetightextractductwor67788.blogmazing.com/35947046/5-simple-techniques-for-fire-resisting-ductwork-insulation