Ice Dam Case Study
Ice Dams are often seen on residential roofs in the Lexington area. The most common causes are inadequate insulation and poor attic ventilation. Ice dams occur when the outside temperature is below freezing and snow is present on the roof. Homes with poor insulation allow heat to escape from the living quarters into the attic. If the roof system is not properly ventilated, the heat will build up in the attic and warm the underside of the roof deck. This process causes the snow on the surface of the roof to melt. Since the outside temperature is below freezing, the melted snow will refreeze when it reaches the gutters or perimeter of the roof. The freeze-thaw process causes an ice dam.
Ice dams allow water to back up underneath the shingles and enter the living space. They can cause damage to the wood substrate, attic insulation, and drywall. Most homeowners contact a roofing contractor, thinking there is a problem with the shingles. Roofing contractors usually recommend installing a heating coil (similar to the house in this case study). Other roof related options include removing the shingles, installing an ice and water membrane, and then installing new shingles to the damaged area. Both options can be very costly.
These two solutions usually prevent water from ice dams from entering the living space. A better solution is to address the heat loss that is occurring inside the house. This will prevent the ice dam from occurring instead of protecting against it.
The Lexington Infrared staff performed the following services for this homeowner -
- Attic insulation was installed in the area above the washing room, eliminating heat loss to the attic and the resulting ice dam.
- Additional attic insulation was added to the remainder of the attic to increasing the R-Value of the attic insulation to R-49.
- The heating coils were removed from the roof, reducing the electrical output.
A follow up conversation to this homeowner on a subsequent snow storm confirmed the elimination of the ice dam through the addition of attic insulation.