How do I keep my attic cool in winter to prevent leaks?

We have a furnace in one corner of our double garage, with ductwork running through the attic of the garage, warming it. This melts rooftop snow, forming ice dams that lead to leakage. How can this problem be fixed?

As you’ve discovered, warm attics aren’t good. They lead to icing, leaks and wasted energy. That’s why keeping the attic cool in winter is necessary, but the main approach should involve duct insulation. There are several options that make sense, depending on your specific situation. If the ducts run close to the attic floor, box them in with an insulated framework. If this isn’t practical, consider having them replaced with factory-insulated metal duct.