Ice dams occur due to uneven temperatures on a sloped roof. The greater the slope of the roof, the more damage an ice dam can do. The process is usually set into action by snow, although an ice storm could also be the trigger.
What happens is that snow or ice on the higher portions of the roof melts. The melt or water flows down the slope until it reaches a point on the roof where the temperature is below freezing. Often, the point that is below freezing is an overhang where there is little or no warming from radiation, convection or conduction of heat.
When the water reaches the lower temperature, it freezes. Water from above continues to flow down the slope and remains liquid until it reaches the ice. Over time, the result is an ice dam. It is a dam in that it traps water behind it. The water can only freeze if it reaches the colder portion of the roof.
Icicles typically form below the dam as some melting occurs during the day. Seeing icicles along the edge of a roof can be a sign that an ice dam has formed.
The damage that occurs to the building is mainly from the water, although the weight of the ice can also cause damage if the overhang on which it rests is not strong enough to support the weight. The water behind the dam searches for an outlet. It starts to work its way through the roofing material and into the insulation.
Once inside the building, the water spreads through the insulation and down the interior walls. It can also spread across the ceiling causing stains and damage to dry wall or other materials.
Ice dams can be prevented in the planning stages of a newly constructed roof. Additional insulation can be used to make sure that the ceiling is airtight. Warm air travels through the ceiling and into the attic space. The warm air rises, causing the higher portions of the roof to be warmer than the lower portions.
Reducing heat loss prevents snow melt. The roof must be strong enough to support the extra weight of the snow. In areas where a large amount of snow falls on a regular basis, there are usually requirements concerning the load that a roof can bear.
Snow rakes can also be used to remove snow and prevent ice dams. Caution is required when using the snow rakes to avoid personal injury and prevent damage to the roofing materials.
There are products like elastomeric coatings, liquid rubber and liquid roof that are one the best products in the market to save your roof from damage.
For product information or ordering visit EPDM Coatings or call them at 855-281-0940.