Icicles indicate the formation of ice dams. What do ice dams indicate?
Icicles form where water is dripping from the roof when snow is melting and the air temperature is less than freezing. Older houses are most prone to ice damming and large icicle formation. Recent building and energy codes addressed this problem and provided solutions. Assuming homes built in last 40 years are properly constructed, they have little to no problem with icicles. This is because the heat loss through the ceiling is small and warm house air does not reach the roof. Current roof ventilation design and adequate ceiling insulation will not allow snow to melt and refreeze as it crosses the cold overhang of the roof. This refreeze forms the ice wall that causes water backup under the roof shingles. This is also how the interior ceiling, wall, wood structure and insulation become water damaged.
Remember mold forms in building materials that remain wet longer than 48 hours.
Today, what can be done about a problem that is knocking on the door? The only answer is to have the ice dam professionally removed by an insured contractor. However, the long term solutions is to have an expert assess attic insulation and ventilation levels, examine for proper roof flashing and shingle underlayment, determine if poor roof design necessitates using heat cables.
Converting roofs to meet a standard that will prevent ice dams is not difficult, but it can be costly.
MN Home Inspector, Minneapolis & St. Paul
ASHI certified inspector, ACI
Kaplan University, Home Inspection Lead Instructor
Rob ‘Pops’ Leslie
Kaplan Professionals, Retired