Water Damming On Roof

After a while this ice builds up until the melting water has nowhere left to go.

Water damming on roof.

So icicles hanging from a roof s edge may be a sign of an ice dam. If necessary use a long handled garden rake or hoe to push it into position. Ice dams occur when snow on the roof is melted by heat that has leaked into the attic warming the underside of the roof. The bottom layer of snow then melts and the water runs down the roof.

This wall of ice is commonly referred to as an ice dam because it traps the melting water like a dam. Lay the hose onto the roof so it crosses the ice dam and overhangs the gutter. Ice dams usually start or worsen after a heavy snow because of snow s insulating properties. The calcium chloride will eventually melt through the snow and ice and create a channel for water to flow down into the gutters or off the roof.

The melted snow turns into water that starts running down the roof surface underneath the snow pack. When the meltwater reaches the colder eaves the part of the roof that extends beyond the walls the water refreezes and creates a buildup of ice along the edge of your roofline says this old house. As the warm air beneath the roof heats the shingles and melts the snow on the roof the water flows down the roofline until it reaches the overhanging eave structure where the freezing temperatures cause the water to refreeze. When the water reaches the colder edges at the bottom of the roof it refreezes forming a wall of ice.

Figure 1 shows a cross section of a home with an ice dam. When the water reaches the overhang and gutter it then refreezes.