Ice Dams on your Roof? What you need to know!
Living in Pennsylvania means embracing all seasons whether it be summer sunbathing, fall leaf jumping, spring gardening, or partaking in winter snow activities. The changing seasons, while beautiful and endearing in their own ways, can bring about some challenges to those that reside here. Concerns for the winter season in Pennsylvania include the frigid temperatures, the freezing precipitation and the effects that these conditions can have on our homes.
As Dale Rimmer of Dale Rimmer Siding and Roofing of Chalfont can attest, a common problem for contractors this time of year is ice damming on roofs. An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow from properly draining off the roof. This causes a back up of water behind the dam that can leak into homes and cause damage to walls, ceilings, insulation, and other areas of the home. Although many northern climate contractors are familiar with the problems associated with ice damming, not all know why they are formed or how to aid in preventing them from forming in the first place. A contributing factor to ice damming can most certainly be obstructed gutters or solar radiation but in reality, improper attic ventilation and insufficient insulation are the largest contributors to the problem.
Ice dams do not occurs every time it snows. They occur when there is a temperature differential that enables the thaw-freeze process to occur, most likely when the outside temperature is twenty-two degrees Fahrenheit or slightly less. This is because temperatures that are warmer generally do not permit for the roof sheathing to be cold enough to refreeze the melting snow.
Because the temperature differential is the root cause of ice dam formation, the best way to prevent them from occurring is to simply keep the entire roof a consistent temperature. In order to keep the entire roof cold, key factors in eliminating the problem are proper sealing, insulation, and attic ventilation. Blocking any air leaks from the living space of the home into the attic, better insulating the attic floor and achieving a balanced airflow system within the attic can achieve this. As Dale will tell you, it is impossible to insulate an attic to the point that the temperature inside the attic will equate to outside ambient air and therefore offers a few other suggestions.
Prevention of ice damming in and of itself is the best way to tackle the problem. By making sure an ice and water shield are applied to the sheathing by code prior to installing the roof, a portion of the problem can be eliminated. According to Dale, by code, the ice and water shield should extend two feet up the heated wall cavity. This means that if the overhang in twelve inches, the ice and water shield should extend twelve inches plus another two feet. In having the ice and water shield applied to the metal of the roof edging, the risk of water getting to the plywood is lessened or altogether eliminated, as there is no longer a direct route.
While the temperature differential is the main cause of ice damming, clogged gutters and gutter leaf covers only add to the problem. According to Dale, “Clogged gutters will cause an ice dam every time the temperatures drop or there is snow and melt because the water is sitting unable to drain.” Clogged gutters are especially detrimental in the instance of an ice storm on top of already fallen snow. The ice freezes on top of the snow on the roof and on top of the clogged gutters and the melting snow has no route to escape. Leaf covers on the gutters also worsen an ice-damming situation as the water gets trapped between the gutters and covers and form an igloo effect. An additional problem that Dale mentions is that while most houses have overhangs on the front of the home, a lot of houses don’t have overhangs on the back. He explains that the reason to have an overhang is so when you have an ice dam, the water runs out away from the house and not down the inside the house which can, over time, rot out the soffit. Ice and water shield attached to the roof edging will take care of the issue.
Unfortunately, the possibility of ice damming is a real threat during a Pennsylvania winter so should a problem occur, seeking the help of a professional is the best bet. Dale Rimmer Siding has been serving Bucks and Montgomery counties since 1982 and would be happy to be of assistance.
Contact us for more information.