We always urge our customers to have their duct work properly sealed with mastic prior to adding new insulation to their attic if they are not sealed up. Leaky air ducts can be a silent drain on your hvac unit. It is something that is easily missed because all it takes is just the slightest hole in a duct line to drive the energy bill up. A lot of the times those holes are hiding beneath the existing insulation deep in a corner of the attic. We take photos of anything we find, so that our customers can see it for themselves.