Have critters? We can help.
Possum/s usually rip your underbelly material, and gain access into your duct work. Someone will need to get under your home, locate the entrance in the underbelly material and then trace all your duct work, this should be sealed to prevent heat loss.
Repair the duct work and inspect it for any type of collapsing from the weight of the possums running on top of it as well. Any matted down insulation will also need to be replaced as it does not retain it's R value once matted. Your duct work should be cleaned after all repairs have been made due to the animals possible using the bathroom in there.