Preventing Ice Dams

Tired of icicles surrounding your home all winter long? Noticed water damage in your attic, or worse yet, the interior walls of your home? Ice dams may be your problem. Worried how it affects the efficiency of your shingles? So many of the issues associated with ice dams can be cured by the proper installation of a new roof, and the accessories and proper ventilation it needs to outlive the long Wisconsin winters.

Ice Dams Defined

An ice dam is a layer of ice that is built up at the edge of the roof that prevents melting snow from draining off of the roof.

Causes and Formation of Ice Dams

An ice dam can occur when a cycle of repeated freezing and thawing causes ice to build up on the roof, blocking the path of newly melted snow as it travels toward the gutters.  Snow accumulates on the slanted roof of a house and warmth coming up through the roof melts the snow from underneath.  If the snow is thick enough, melt water flows down the roof, beneath the blanket of un-melted snow, until it flows onto the eave and into the gutter, where colder conditions on the overhang cause it to freeze. Eventually, ice accumulates along the eave and in the gutter, “damming” up the path of the newly melting snow.  The next batch of melted snow now cannot drain properly, and water continues to build up and eventually backs up underneath your shingles where it can cause major leaks.

Can Ice Dams Be Completely Prevented?

Under extreme conditions, with heavy snow and severe cold, almost any house can have an ice dam, whereas a house that is poorly insulated and ventilated will have ice dams even during normal winter weather. While many of us have taken steps to reduce the ice dams that can occur during Wisconsin winters, preventing ice dams in extreme weather, as we’ve experienced recently, requires a few additional measures on the part of the homeowner.

How Can I Minimized The Chance Of Having An Ice Dam?

• Keep the roof cold by keeping the attic cold.
  • Install more insulation in the attic floor.
  • Seal bypasses into the attic.
  • Draw more outside air into attic through gable and eave vents.
• Install slippery metal roofing along the eaves so that snow and ice slide off more easily.
• Before installing new shingles, install an adhesive, waterproof, rubberized ice-shield membrane on the sheathing to seal around nail holes and protect the sheathing from backed-up water.
• Switch to a warm-attic system. Make your attic part of the conditioned space of your house. This requires that you insulate the attic roof from both sides, insulate the exterior walls of the attic, and install energy-efficient attic windows.
• Install electric roof de-icing cables to create a heated drain path that allows melt water to drain off the roof through the gutter and downspout system. Roof de-icing cables should be installed by an electrical contractor per the national electric code on a dedicated GFCI protected circuit.

What Maintenance Does My Roof Need In Winder?

Homes that have taken all the permanent steps possible to prevent ice dams may still see some ice build-up during heavy snowfalls.  This is not a sign that your preventative measures are failing, but simply a reminder of the reality that no system can entirely prevent ice buildup.  In addition to alterations to the structure of your home, ice dam prevention should include the following regular maintenance:

• Make sure attic vents aren't blocked.
• Keep gutters clean.
• Remove excess snow with a roof rake.
• Hose off the roof with tap water on a warm day. (Note that water run-off could damage shrubbery.)
• Break up ice dams by creating ice channels to drain water.
• Fill an old pair of pantyhose with calcium chloride snow melt and lay it across the dam. (Do not use rock salt as it can discolor the roof!)
• Address snow build-up early, before it has a chance to melt.
• Hire a company to steam the roof if other measures cannot control the ice buildup.

Things Not To Do

• Do not chop ice off the shingles. You will damage the shingles.
• Do not use a blowtorch. You could burn your house down.
• Do not throw anything on the roof that cannot be retrieved. This can cause rain gutter plugging.
• Do not take your gutters off your home!  The water will not back up without gutters, but will instead drop down to the ground and into your foundation.