Then and now - a look at an HVAC remodel and the results. In this video, Matt Risinger, master builder, is in the attic of a 10-year old lake house. Before the HVAC remodel, the air handling equipment was tested and there was approximately 25% duct loss in the unit in the attic. When the attic was still unconditioned, the static was between 120 and 130 degrees on a typical day. There was a lot of loss out of that system. For every dollar spent, 25 cents just went through the ductwork without benefiting the house. After the remodel, there's a sheet metal plenum on the new unit. Latex-based mastic is used to seal all of the joints. Instead of a 25% loss, the loss should now be a more manageable 5% to 7%, possibly less. All of the air losses, large and small are captured by putting mastic on the seams.