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The serene sight of a roof blanketed with a fresh layer of snow can be a mesmerizing visual straight out of a winter postcard. However, this image also rings the alarm bell for the possible dangers that come with it. This article aims to answer this question and explore the risks of having too much snow on your roof.
What Are The Dangers of Heavy Snow on The Roof?
It is crucial to understand the dangers of heavy snow on your roof. You must remove the snow load as soon as it starts, as it might cause the following issues.
Ice Dams
One of the foremost concerns with heavy wet snow on your roof is the formation of ice dams. The warm air escaping from your house, particularly the attic, can cause the lower layer of snow to melt. This melted snow then refreezes at the edge of your roof, creating an ice dam. These dams can form picturesque but dangerous icicles, which can block the natural flow of water off the roof, leading to potential leaks and structural damage.
Roof Leaks
As the ice dam grows, the trapped water has nowhere to go but under your roofing material. If your roof is composed of asphalt shingles, slate shingles, or any other material that isn't perfectly water-tight, this can cause roof leaks. A leaky roof damages your home's interior and indicates an overburdened roof that might be on the brink of more severe structural issues.
Roof Sagging or Caving In
A sagging roof is another red flag that your roof is struggling under the weight of too much snow. Heavy snow loads can stress your roof's structure, causing a noticeable curve or sag in the roof material. If you see new cracks in the interior door frames or hear creaking sounds, it's a clear indication of structural issues which, if left unaddressed, could lead to a catastrophic roof collapse. It's imperative to keep an eye on these signs during heavy snowfall periods to ensure the safety of your home.
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How Much Snow Can a Roof Hold in Pennsylvania?
While the design requirements for roof snow loads can vary greatly across different regions, Pennsylvania, like most states, follows the International Building Code (IBC). The code sets the standards for building design, including how much snow a roof can hold.
According to the IBC, the minimum roof snow load for any building is 20 pounds per square foot (psf). So if your roof snow loads equal more than this figure, you may want to clear it.
However, certain areas in Pennsylvania, especially those prone to heavy snowfall or located at higher altitudes, might have higher local requirements. This is often referred to as the ground snow load.
To understand how much snow this translates to, let's again consider the weight of different types of snow. One cubic foot of fresh, cold fluffy snow typically weighs about 7 pounds, while the same volume of wet, heavy snow can weigh up to 20 pounds. So, if your roof is designed for the minimum requirement of 20 psf, it could safely hold approximately 3 feet of fresh snow or about 1 foot of wet snow.
Required roof snow loads can be influenced by several factors, including the type of roof - whether it is a flat roof or a sloped roof, the roofing material, and the age and condition of the roof. Flat roofs, for instance, are more at risk as they can accumulate snow more easily than sloped roofs, where snow can often slide off.
Factors That Influence How Much Snow A Roof Can Hold
While the ground snow load and the type of snow are primary considerations in determining how much snow a roof can hold, several other factors can influence a roof's ability to handle snow.
Roof Design and Construction
The design and construction of your roof play a critical role in determining how much snow it can hold. Flat roofs, for example, are more prone to accumulate heavy snow loads because the snow cannot easily slide off as it would on a sloped roof.
The angle of a sloped roof also influences how much snow it can hold. The steeper the slope, the less likely the snow will accumulate. Fluffy snow blowing over such a roof can easily roll off.
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Roof Material
The roofing material can also affect how much snow a roof can handle. For instance, metal roofs are more slippery, which helps snow and ice slide off, reducing the overall load. In contrast, roofs made of asphalt shingles or slate shingles provide more friction, leading to more snow accumulation.
Age and Condition of the Roof
Older roofs or those in poor condition may not hold as much snow as newer, well-maintained ones. Structural degradation over time can weaken a roof's ability to withstand heavy loads. Regular inspections and maintenance are key to ensuring that your roof is in good condition and up to the weight of winter snow.
Roof Insulation
The roof insulation quality can indirectly influence the amount of snow a roof can hold. Poorly insulated roofs can cause heat to escape, leading to the melting and refreezing of snow, which forms ice dams. These dams can trap additional snow and add considerable weight to the roof.
Local Climate
The local climate plays a part in determining how much snow a roof can hold. Roofs in mild winters may not be designed to hold as much snow as roofs in harsh, snowy winters.
Wind Direction
Wind direction and speed can influence snow distribution on residential roofs. Wind can cause snow to drift and accumulate in certain areas, creating uneven loads on your roof.
Conclusion
While you cannot control the snowfall, understanding how much weight a properly constructed roof can hold and the warning signs of excessive load can help prevent disaster. It is important to watch the snow loads on your roof during record-setting or extended periods of snowfall.
Equity Roofs is among the companies that can install a strong wind to withstand those stressful conditions such as snow. It is important to have a strong and properly maintained roof for such conditions.
Read also our blog on How to Install Snow Guards on Metal Roof?.