If you have icicles on your house, you have a problem. When we think of icicles, we usually think of a beautiful white winter scenery. However, icicles are responsible for over 1000 deaths per year and thousands of dollars in roof, attic and interior wall damage. In the following article, I'm going to explain what causes icicles, and what you can do to prevent them from damaging your roof and attic systems.
If icicles are forming on your gutter line, you either have no insulation, improperly installed installation or limited insulation in your attic space. This condition, combined with poor attic ventilation, allows warm air from the house to escape into the attic, increasing the attic temperature above freezing. If there is snow on the roof, the snow will melt, and the water runs down over the soffit and into the gutter. Since the soffits and gutters are not above heated areas, the water refreezes and an ice dam forms at the gutter line. (See Pictures Below).
As the snow continues to melt, the water will continue to drain and back up at the ice dam. Water that backs up behind the ice dam can leak under the shingles and into the home, causing damage to the roof, interior walls/ceilings, and installed insulation.
Inspect Your Attic Insulation & Ventilation
Improving the insulation and ventilation in your attic space is the best way to prevent ice dams and icicles from forming. Have a qualified contractor evaluate your attic insulation, depending on what part of the country you live in and the energy source used to heat your home, your typical attic space R-Value is between R38-R60. (See R-Value Photo)
During inspections, we often see insulation installed over the soffit vent or up against the roof decking near the soffits. This will block the air flow from the soffit vents and warm the underside of the roof deck, causing the snow to melt short of the gutter (Figure I016 & I015). Installing ventilation baffles will prevent insulation from blocking the vents, allowing air to properly ventilate the attic space.
Under insulated attics will allow the warm air from the house to escape into the attic space. The temperature in the attic space should be about the same as the exterior temperature. If the outside temperature is below freezing and snow is melting off your roof, you likely have an under insulated attic space. This condition, along with poor attic ventilation will trap warm air in the attic space. The warm air will condensate on the roof decking and nails, promoting an environment for mold growth and ice dams.
Your roof and attic system is designed to shed water away from the house, keeping the interior of the home dry and aduquatly conditioned. If someone alters any part of these designed systems without consultation of a qualified contractor, the attic system will no longer work as intended. If you notice icicles along your gutters, or the snow melting off your roof in below freezing temperatures, you should consider having your attic system inspected. Adding insulation and ventilation baffles is cheaper than replacing damaged walls and roof sheathing from water leaks and mold growth.
Chris Heywood, President
Horizon Point Inspections, LLC