An ice dam is a buildup of ice on a roof created by repeated freezing and thawing cycles, typically toward the lower portions of the roof or in the gutters. An ice dam can be problematic because it blocks additional snow and water from draining off the roof.
Sheffield Metals International, a leading provider of materials for the metal roofing industry, has worked with thousands of customers across the United States, many of whom live in cold climates and have had to deal with ice dams. In line with Sheffield’s goal of educating metal roof owners as best as possible, we’ve put together this quick guide on ice dams, including how they form and what steps you can take to prevent them.
If you live in a cold climate and are concerned about an ice dam forming on your roof – or are looking for a solution for an ice dam on your roof right now – this article will help.
What Causes an Ice Dam to Form?
Ice dams usually form after heavy snowfalls and in extreme cold. Here’s how it happens:
Snow falls and collects on the roof. Heat from the inside of the home rises up and warms the central portions of the roof, causing the snow to melt. Gravity pulls this melting snow down to the lower edges of the roof where the surface is colder and usually not insulated. And it’s at those lower edges of the roof – usually on the roof eaves, overhangs, or in the gutters, where that melted snow collects. The water freezes when it contacts the colder portions of the roof, begins to thaw as temperatures rise in the daytime, then refreezes at night. This cycle repeats again and again, causing a wall of ice to form.
This ice dam prevents other snow, water, and ice from draining off the roof, creating an accumulation on the roof that can cause both aesthetic and functional issues.
Ice is heavy, and when it forms it expands, which can pull trim apart and even affect the seams of the panels.
Are Ice Dams Harmful to Metal Roofs?
Aside from the aesthetic considerations – a huge mound of ice and snow building up on your roof can be unsightly – are ice dams really that harmful for metal roofs? It all depends on the severity of the ice dam, but if it’s bad enough, they can cause serious damage to your roofing system, including gutter and fascia damage and even black mold inside your home:
- Gutter damage: Ice dams often form in gutters, as the water can easily collect here and freeze, melt, and refreeze. If enough ice builds up in the gutter, it could cause your entire gutter to fall.
- Fascia damage: Damage to your gutter would in turn damage the fascia, stripping the paint and potentially tearing it down.
- System damage: In the worst cases, ice dams can be so severe that they lift the edges of your metal roof up, which could put the entire system in jeopardy.
- Interior Damage: Ice dams could also penetrate the interior of a home or building, letting water leak into the insulation and leading to other potential issues like black mold.
Prevention Methods and Solutions for Ice Dams on Metal Roofs
Steep-Slope Roofs
If you’re building or designing a new home in a cold climate, consider the slope of your roof.
Metal roofs with steeper slopes – steep slopes are usually anything considered above a 3/12 pitch – drain snow, ice, and water more effectively. This is why you typically see steeply-pitched roofs with broad eaves in the Alps – it’s a very effective design for shedding snow.
Even if a low-slope roof might suit your aesthetic preferences, a steeper slope may be the better functional choice if you live in a cold weather region.
Oversized Gutters
Ice dams can also form because the buildup of water and snow doesn’t have anywhere else to go. It piles up in narrow gutters and clogs the drainage system.
Installing bigger gutters that can handle this flow of snow and water can help prevent ice damming. With oversized gutters, water can flow freely, limiting the chances of ice buildup.
Just keep in mind that with bigger gutters, you’ll likely want to get bigger downspouts and overall better supports that can handle the additional weight, too, that can handle the influx of water. When you change one part of your roofing or drainage system, it’s important to keep in mind how this will affect the rest of the system.
Heating Products
You can also find many products that use radiant heat to prevent ice dams from forming on roofs.
Products like nVent RAYCHEM use heating cables that run along the edges of your roof. These heating cables use sensors and a power controller to monitor temperature and moisture levels. When the temperature and moisture reaches a set point, the cables heat up, effectively preventing ice formation.
Remember that products like this will require a power source – you may need to invest in an electrical box to hook the system up. Contact your manufacturer for best installation practices to not void any warranties.
Ventilation and Insulation
Improving insulation within your house prevents warm air from escaping the conditioned areas, which limits excessive energy costs but also protects your roof deck from warming too dramatically. This equalizes the temperature of the central portions of your roof and its eaves, reducing the chances of the freezing, thawing, and refreezing ice dam cycle.
Making sure your attic has adequate ventilation is also a key factor in ice dam prevention. Moving warm air out of the building helps keep the roof deck at a more consistent temperature.
Regular Maintenance and Inspections
A foolproof way to avoid many common problems on a metal roof is to keep your roof on a regular maintenance and inspection schedule. At least once a year is recommended, but you might want to consider getting your roof inspected after a heavy snow or ice storm. Inspections and regular maintenance will ensure your gutters and downspouts are clear and help prevent issues like an ice dam from causing real damage to your roof.
If you do notice that you have an ice dam on your home, a contractor can help identify how serious it is and offer potential solutions. Often, the solution may be a combination of options listed in this article. You might need oversized gutters and heating cables, for example, to ensure that your home is safe and protected from ice dams.
While it can be tempting to find at-home solutions and try to solve the situation yourself, we always recommend having a professional take a look. Every situation is unique, and a qualified contractor will understand how to approach your specific home or building and find the right solution for an ice dam.
Looking for More Cold-Weather Guidance for Your Metal Roof?
If you live in a cold-weather climate, there’s a lot to keep in mind to keep your metal roof in good shape. Feel free to check out our additional articles and videos related this topic:
Cold Weather Metal Roofing: Assembly Design, Snow Loads, Ice Dams – Sheffield Metals
Metal Roofing and Snow Retention: Snow Guards, Snow Fence, Snow Rail – Sheffield Metals
How to Choose the Right Snow Retention System for Your Roof – Sheffield Metals
How to Install Snow Guards on a Metal Roof – Sheffield Metals