Protecting Roofs from the Elements

Any homeowner can tell you that ice damage repairs can get pricy. Today, we’re addressing two major sources of ice-related home damage: ice dams and hailstorms. We’re breaking down what these phenomena are, what causes them, and what steps to take to ensure the roof is adequately protected, saving homeowners time, repair costs, and lots of headaches.

Ice Dams

So, what exactly is an ice dam?

Ice dams are caused by a build up of ice on roofs where the temperature difference causes snow to melt and water to freeze at the same time in different areas. When the snow melts on the warm surface, it causes the water to run off and refreeze into ice on a colder surface of the roof (typically the edge), forming long icicle-like structures along the roof. The term ice dam comes from the fact that these dams often cause a backing up of runoff since they build up in and around the gutters.

Once formed, ice dams can cause some major issues for homeowners. The huge chunks of ice that form can damage property and even cause water leakage into the attic as the ice refreezes and forces its way through the shingles.

The two contributing factors of a warm attic, a main cause of ice dam formation, are lack of ventilation of the outside air and too much interior air leakage through the ceiling. If the attic isn’t airtight, warm air from inside the house can creep up into the attic, and if the ventilation isn’t working properly, the attic heats up enough to start melting some of the snow on the roof. Even with just a small dusting of snow, any amount of snow build-up on the roof can result in ice dams. Making matters worse, a large amount of snow on the roof can even act as insulation for the house, and as a result, make the attic interior warmer.

There are a few different solutions for ice dams. Many locations require peel-and-stick waterproof membranes to be placed under the roof shingles to reduce the amount of water getting into the attic. This solution, however, is not preventative. It just reduces the risk. Shoveling the snow off is also an alternative but not recommended due to the roof damage and personal injury risk involved.

Preventative solutions to ice dams include installing a metal edge on the roof to act as a slip plane to keep the ice from building up, electrical wiring on the edge of the roof, and most importantly, ensuring that your attic ventilation is working and your interior partition walls are airtight. Furthermore, moving the roof deck inside the thermal envelope of the house is a great way to maintain a consistent temperature since the insulation keeps it warm and eliminates thermal bridges.

Hail-Resistant Roofing

Another ice-related roof killer is the dreaded hail, frozen precipitation that accompanies some thunderstorms. With spring on the horizon, it’s important to make sure the roof is protected against these potentially dangerous hailstones.

On average, hailstorms cause $10 billion in damage to homes annually, with roof repairs accounting for the bulk of the costs. While not typically life threatening, hail is an incredibly costly repair expense for insurance companies and homeowners. This is especially true considering the damage costs are very consistent year after year. Along with these costs comes plenty of annoyance considering the numerous repairs that must be done, particularly in areas that get frequent hailstorms.

Tanya Brown-Giammanco, director of disaster and failure studies at the National Institute of Standards and Technology (NIST) and the former managing director of research at the Institute for Business and Home Safety (IBHS), ran a series of tests in which lab-created hailstones were launched at test roofs. She and her team were able to collect various metrics, which proved incredibly useful in creating solutions to combat the damage from the hailstones.

The best chance at reducing hail damage is by choosing a roofing shingle with an impact-resistance rating; the best options have a “Good” or “Excellent” rating in the IBHS performance rating scale. It is also good practice to seal the roof deck with flashing tape, fortify the edges, and raise the nailing schedule. While these steps should decrease the damage done by two-inch-sized hailstones, most roofing will have a tough time resisting damage when the stones get to be three or four inches in radius. Thankfully, the stones in most hailstorms stay under two inches.

Be Prepared

By utilizing these tips, you can better protect homes from extreme weather and help ensure that homeowners don’t end up paying the consequences down the road in costly home repairs!

This content was taken from the podcast “7 Minutes of BS (Building Science)” from Protradecraft.com.