After a comparatively gentle winter in 2017, the northern phenom of ice dams are back in West Michigan with a vengeance. Sub-zero conditions and building snow have homeowners scrambling to prevent the kind of problems nearly everyone experienced in the harsh winter conditions of 2014.
What Causes Ice Dams?
You might think the obvious answer to this question is “snow.” However, that’s only part of the complex interaction that actually causes ice dams. The variables that interact include the amount of heat loss from a house, snow cover, and outside temperatures. For ice dams to form there must be snow on the roof, and, at the same time, higher portions of the roof’s outside surface must be above 32°F while lower surfaces are below 32°F. For a portion of the roof to be below 32°F, outside temperatures must also be below 32°F.
The snow on a roof surface that is above 32°F will melt. As water flows down the roof it reaches the portion of the roof that is below 32°F and freezes. Voila! – an ice dam.
The dam grows as it is fed by the melting snow above it, but it will limit itself to the portions of the roof that are on the average below 32°F. So the water above backs up behind the ice dam and remains a liquid. This water finds cracks and openings in the exterior roof covering and flows into the attic space. From the attic, it could flow into exterior walls or through the ceiling insulation and stain the ceiling finish.
Here’s a brief guide of what to do now, and what to do in the future to help prevent breaches from built-up ice dams. Call us if you need assistance, and never climb your roof in winter conditions.
What You Can Do Now:
1. The Roof Rake is your friend. It may not SEEM like it’s your friend when you’re bracing against the arctic chill and gently scraping the accumulating snow off your roof, but don’t worry, the workout will warm you up soon enough! Reducing the snow load on the approximate 2 feet to your warm wall line will help stop water from backing up under your shingles because you’re eliminating one of the ingredients necessary for the formation of an ice dam. However, take care not to damage the roofing materials. To prevent damage, we like roof rakes that have wheels like the Garelick shown right.
2. In an emergency situation where water is flowing into the house structure, making channels through the ice dam allows the water behind the dam to drain off the roof. Hosing with tap water on a warmer day will do this job, or loading calcium chloride into nylons will also melt out a channel. Work upward from the lower edge of the dam. The channel will become ineffective within days and is only a temporary solution to ice dam damage. We do not recommend chiseling out a channel as you may cause substantial damage to your roofing material.
3. Something to try: Take a box fan into the attic and aim it at the underside of the roof where water is actively leaking in. This targeted dose of cold air should freeze the water in its tracks. This will only work if your attic is already vented well enough for the air to be very cold. Don’t do this if the attic air is warm.
Premier Roofing can assist in emergency ice dam remediation that requires getting up on the roof, channeling, and planning remediation measures. Do not go up onto the roof yourself without a safety line and do not use tools to channel into the ice – Contact Us for help. Read on for remediation recommendations below regarding the installation of water shield and correcting attic venting to create a more uniform temperature and improve air flow.
What You Should Do Later:
A three-pronged attack can help you combat future ice dam damage. First, you want to create uniform temperatures across the surface of your roof. This is where insulation and attic ventilation come into play. In addition, you want an impenetrable barrier to prevent water damage even if a dam develops. This is where modern underlayment options can vastly improve the protection of your roofing system and deck.
Sealing Areas Where Heat Transfers to the Attic:
Heat from the house travels to the roof surface in three ways: conduction, convection, and radiation. Conduction is heat energy traveling through a solid. Heat can transfer from inadequate or ruined (wet) insulation, through chimneys, ductwork, or exhaust vents. One way to help identify air leaking is called a blower door test. Infrared cameras will also help identify areas where additional sealing and insulation should be added. Long-term, sealing the “envelope” of your home heat from the attic will help avoid ice dams overall.
- Seal all points where warm air leaks from the living space into the spaces immediately below the roof sheathing.
- Insulate the living space well enough to prevent conduction and convection of heat through the ceiling.
- Vent the space between the insulation and the roof sheathing, so any heat that does leak through is carried away.
Ridge Vents – An Economical Improvement
In the old days, homes were built with soffit vents alone. More current ventilation strategy depends on the installations of ridge vents to help keep the roof temperature uniform. This will improve air flow that cools the deck. However, once snow-covered, ridge vents are less effective, so are not a stand-alone solution in an ice dam emergency. But long-term, ridge venting is shown to extend the life of your roofing materials and improve the energy envelope of your home throughout every season, including winter.
Install Water-Repellant Membrane
This extra protection will have to wait until you’re ready for a rip-off and replace of your shingles, but don’t miss the opportunity when getting a new roof to install today’s space-age water-repellant membrane. The extra protection is wholly worthwhile.
This video by roofing material manufacturer, Certainteed, shows the installation of its Winter Guard underlayment, one of several options available through Premier Roofing:
Adding Heat Tape – Sometimes
If carefully installed and turned on only during freezing conditions, a zig zag line of heat tape on trouble spots near your eaves may help reduce ice damming. However, heat cable doesn’t fix the root cause of the problem: too much snow on a roof that’s overheated because warm air is leaking into your attic. At best, heat tape is a band-aid solution. However, there are some instances where it can improve conditions when all other efforts have been exhausted.
If you need help managing your ice dam, Contact Us.