Snow on Roof and the Problems
- Immediate action:
- Remove snow from the roof. This eliminates one of the ingredients necessary for the formation of an ice dam. A "roof rake" and push broom can be used to remove snow, but may damage the roofing materials.
- In an emergency situation where water is flowing into the house structure, making channels through the ice dam allows the water behind the dam to drain off the roof. Hosing with tap water on a warm day will do this job. Work upward from the lower edge of the dam. The channel will become ineffective within days and is only a temporary solution to ice dam damage.
- Remove snow from the roof. This eliminates one of the ingredients necessary for the formation of an ice dam. A "roof rake" and push broom can be used to remove snow, but may damage the roofing materials.
- Long-term action:
- Increase the ceiling/roof insulation to cut down on heat loss by conduction. State code requires an R-value of 38 above the ceiling for new homes. In narrow spaces, use insulation products with high R-value (6-7) per inch.
- Make the ceiling air tight so no warm air can flow from the house into the attic space.
- Increase the ceiling/roof insulation to cut down on heat loss by conduction. State code requires an R-value of 38 above the ceiling for new homes. In narrow spaces, use insulation products with high R-value (6-7) per inch.
Both of these actions will increase the snow load that your roof has to carry because it will no longer melt. Can your roof carry the additional load? If it is built to current codes, there should not be a structural problem. Roofs, like the rest of the home, should have been designed to withstand expected snow loads. In Minnesota, plans showing design details to meet expected snow loads are usually required to receive a building permit. The plans for your home may be on file at your local building inspection office. To help you understand the plans, or if you cannot find plans for your home, you may want to contact an architectural engineering firm. A professional engineer should be able to evaluate the structure of your home and answer your questions about the strength of your roof.
- Natural roof ventilation can help maintain uniform roof temperatures, but if the long-term actions described here are done effectively, then only small amounts of roof ventilation are needed to maintain uniform roof surface temperatures. If heat transfer has been reduced substantially, then snow will build up on the roof and cover natural roof ventilation systems, reducing attic ventilation rates. Natural attic ventilation systems are needed to dry the attic space and remove heat buildup during the summer.
Mechanical attic ventilation IS NOT a recommended solution to ice dams. It can create other attic moisture problems and may cause undesirable negative pressure in the home.
