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What is an Ice Dam?

Figure 1

A common cause of leaks during the winter months is ice dams.  Ice dams occur when snow on your roof melts, but freezes again in colder sections of your roof typically at the eave (edge).   The ice dam then prevents water from draining properly off the roof when the snow melts. Water builds up with nowhere to go, but through the roof & into your attic space.

The moisture entering a building from ice dams can lead to mold & mildew as well as structural damage to wood and discoloration of walls and ceilings. 

Read below to learn how to protect your home, HOA or Commercial/Multi-Family property from costly ice damming.

Improper Intake Ventilation

No matter the ventilation system on your property, the heat from inside will get into the attic.  If the ventilation system is not working properly, that warm air will stay in the attic, heat the roof and the snow will melt from the bottom side.  Remember, you want your property warm in the winter, but your attic should be as close to the outside temperature as possible.  You do not want a warm roof in the winter.

A balanced ventilation system, 50% intake & 50% exhaust is essential in order to remove the warm air from the attic space.  The most common issue seen is inadequate intake, meaning no fresh/cool air can move into the attic.

Ensure that when you’re replacing the roof on your home, you discuss the installation of a balanced ventilation system with your contractor.  You can add intake ventilation to your soffits at any time and this will drastically reduce your chances of ice damming and interior leaks.

Blocked Vents

Check where your attic insulation is laying.  If it sits on top of your soffit intake ventilation, that vent is blocked and air flow is restricted.  It’s never too late to have a professional move the insulation away from vents.

When you or your contractor install insulation in your attic, discuss the location of the vents with your contractor to make sure they remain open and unblocked.

Attic Too Hot!

Improperly heating your attic can lead to many issues with ice and water build up on your roof. Many people believe it’s best to keep the attic warm throughout winter, but actually, it’s best if the attic is as close to the outside temperature as possible. If the attic is too warm, it melts the underside of the snow on the roof, causing water to run down. However as it approaches the edge, the cold air from the soffit will freeze it, causing an ice dam. (See Figure 1 above) 

If the snow on your roof is melting significantly faster than the rest of your neighbors, this could be cause to check the temperature of your attic to ensure that it’s not overly warm.

Clogged Gutters and Downspouts

If your downspouts and gutters are clogged, there’s nowhere for water to drain. This water builds up, freezes and causes an ice dam to form. Make sure that you are getting your gutters cleaned once a year (in the fall is best) to prevent blockages in the winter.

Additional Protection . . .

Use a self-adhering leak barrier called Ice & Water Shield.  I&WS is a self-healing waterproof membrane that will keep moisture out of your attic space should you experience an ice dam.  Many local building departments require the use of I&WS when installing a new roof.  Be sure to ask your contractor to research the codes in your area.  Even if the local building department does not require I&WS, be sure to have it installed if you live in a snowy cold winter climate.  You want to have the I&WS installed at the eaves and cover the roof deck 24’’ inside the warm wall.

Do you believe an ice dam is causing damage to your roof? Are you experiencing winter-time leaks or have you found mold in your attic? Contact us and our team will come and take a look!