The most common problem he said is the lack of sufficient attic vents and moisture venting from bathrooms to attics. Maybe you put aluminum siding over your wood siding one year. Then the gutters rust and you replace them. Then 20 years later, the roof goes bad and you get a new one. It's a big misconception that adding insulation is the answer.
People typically add more insulation, or ventilation in the attic, to stop ice dams.
But the measure that's missed is air sealing. If you don't plug the holes around chimneys, dropped soffits, the tops of plumbing walls, any hole or cavity, you'll still gets drafts and heat loss. Their damage is preventable, however, the men agreed. Remove roof snow before it can dam, or neutralize the dam by melting the ice or carefully creating a channel for runoff, they advise. For long-term protection, consider installing a rubberized roof underlayment called an ice and water barrier.