Minimizing & Eliminating Interior Leaks: The most probable cause of ice dams is when warm air from the rooms in your house starts seeping though the insulation and into the attic.
The warm air goes around your ceiling through exterior joints or through other openings such as recessed lighting fixtures, retractable attic stairs, chimney or plumbing.
Another possibility is that your attic is poorly insulated or ventilated. What happens when there is poor ventilation is that this warm air accumulates in the attic and warms the underside of the edges of the roof.
Because of the cold temperature outside your home, the top outside layer will stay frozen while the warm decking will melt the bottom layer of ice turning it into liquid water.
This water will start running down the shingles until it meets at the gutter line, and because there is no where else for it to go, it forms a pool of water, which then backs up underneath the shingles and enters the attic through seams in the roof deck.
Here are some tips to help you minimize these Ice Dams from occurring;
-Keep the attic properly insulated.
-Never cover the attic soffit air intake vents with any type of insulation.
-Make sure that the attic has enough air exhaust outlets and that the airflow is distributed evenly through the entire attic.
-Install an ice and water shield protector at the eves and under the shingles, this will prevent water from entering your home.
-Electric heat tapes should be installed in all gutter systems. If you should notice any signs of excessive moisture around the windows you should seal around the window to ensure that it is securely air tight.
-In a nutshell the very best way to prevent ice dam problems is by keeping the roof cold.
-Prevent heat in the attic from heating the underside of the roof by installing heavy insulation to the attic floor and ventilating the attic securely.
-Install lots of soffit and ridge vents and be sure and cover the top plate of the exterior stud walls.
To prevent the insulation from blocking the airflow from the soffit vent to the ridge vent you will have to install baffles over the insulation by the top plate.
