How important is grease containment? If you have a commercial cooking operation, rooftop grease damage is something that needs to be dealt with. Fats, oils, and grease are discharged from your upblast hood exhaust fan and collects on your roof. This creates a deadly fire hazard and liability for your business. Also, since your business can be held responsible for polluted storm water systems and grease runoff, rooftop grease containment is something you need to control.