The only snow left on the roof is out on the eaves. The massive icicles indicate that this home is very vulnerable to ice damming and roof leakage. The damage starts with rooftop snow melting and then freezing when it reaches the cold eaves. Insulating this attic to R-38 would probably save this homeowner hundreds of dollars a year in heating and air conditioning costs and would make this home more comfortable as well. We insulate attics to keep heat from escaping out of the living space and to keep the attic cold and dry.
Most homeowners understand that.
However, insulation is only half of the protection that a good attic needs. Insulation doesn't stop air from leaking and taking heat and moisture with it. A home performs well only when both heat and air are controlled. Conduction occurs when heat flows from warm materials to colder materials. Convection occurs when warm, moist air rises and leaks out of the living space and carries heat with it.