How Weather Conditions Affect Your Roof

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By George Taylor

Updated: Jul 11, 2024

8 min read

Snowy winter day in countryside
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    Your roof is the stalwart guardian of your home, a barrier against the elements that rage above. But even the sturdiest roof can succumb to the relentless assault of weather over time. Understanding how different weather conditions impact your roof in your specific region is vital for proactive maintenance and ensuring its longevity. 

    Rain: The Persistent Threat

    Rain is a common threat to roofs, with its impact varying by region and intensity. Environment Canada reports an average annual precipitation of 560 mm, but this varies significantly across the country. Heavy rainfall can overwhelm gutters, leading to overflow, water pooling, and foundation issues. The CRCA notes that clogged gutters cause over 5% of roof leaks. Wind-driven rain, especially with high winds, can pry shingles loose or tear them away. ARMA studies show that wind uplift is a major cause of shingle failure, with high winds responsible for nearly 25% of roof failures.

    Regional Considerations:

    • British Columbia: The Pacific Coast experiences heavy rainfall, with some areas receiving over 2,000 mm of rain annually. Metal roofs or asphalt shingles with a high water resistance rating are suitable options. Regular cleaning of gutters is essential to prevent water pooling and potential leaks, especially during long stretches of rain. Homeowners in this region would benefit from consulting with a professional like a Vancouver roofer to ensure their roofs are adequately prepared for heavy rainfall.
    • Atlantic Canada: This region receives an average of 1,000 mm of rain annually, with some areas exceeding 1,500 mm. Regular cleaning of gutters and proper ventilation are crucial to prevent moisture buildup under shingles. Metal roofs, like standing seam or metal shingles, are excellent choices due to their water-shedding properties. Additionally, the use of underlayment with enhanced water-resistant properties can provide an extra layer of protection against persistent moisture. 

    Winter's Icy Grip

    Snow and ice pose unique challenges for roofs, particularly in colder regions of the country. Excessive snow accumulation can put a significant strain on your roof. The National Building Code of Canada (NBCC) specifies the design of snow load for different regions, ensuring roofs can withstand the expected weight of snow. However, local building codes may specify a higher snow load requirement depending on the area. Warm air escaping from the attic can melt snow near the eaves, refreezing into ice dams that prevent proper drainage. This can lead to water backup under the shingles and leaks into the home's interior. The Canadian Institute of Plumbing & Heating (CIPH) recommends proper attic ventilation to prevent ice dam formation.

    Regional Considerations:

    • Prairies: These regions experience heavy snowfall, with some areas receiving over 200 cm annually. Regular roof snow removal is essential, especially after major snowfalls. Steeper roof pitches help shed snow naturally. Metal roofs are a good option as they shed snow more efficiently than asphalt shingles. The use of heat cables along eaves can also help prevent ice dam formation.
    • Mountain Regions: These areas experience heavy snowfall and potential for the ice dams. Proper ventilation in the attic is crucial to prevent warm air from melting snow. Metal roofs are a popular choice due to their ability to shed snow and resist ice dam formation. Some mountain communities have specific roofing requirements to handle extreme snow loads.

    The Sun's Relentless Assault

    While sunshine might seem harmless, it can wreak havoc on your roof over time, particularly in regions with intense solar exposure. The sun's UV rays break down asphalt shingles, making them brittle and prone to cracking. The CRCA estimates that asphalt shingles in the sunniest parts of Canada can lose up to 1/3 of their lifespan due to UV degradation. This is particularly significant considering that the average lifespan of asphalt shingles is 18–25 years under normal conditions. Extreme heat can cause asphalt shingles to curl and buckle, compromising their integrity. The phenomenon known as “thermal shock,” where rapid temperature changes cause materials to expand and contract, can also lead to premature aging of roofing materials.

    Regional Considerations:

    These regions experience high levels of sunshine hours. Clay tile roofs or metal roofs with a high solar reflectance rating can be good options for these areas. Reflective roof coatings can also help to deflect sunlight and reduce heat absorption. Studies have shown that reflective roofs can reduce cooling energy costs by up to 15% in hot climates.

    Hail: Nature's Roof Wrecking Balls

    Hailstorms can cause significant damage to roofs in a short period, posing a particular threat in certain regions of the country. The larger the hailstone, the more significant the damage.

    Regional Considerations:

    Hailstorms are a frequent occurrence in this region, with some areas experiencing an average of 10 hail days per year. Impact-resistant shingles are a wise investment for homeowners. These shingles are tested to withstand impacts and meet specific hail standards set by national building codes. Metal roofs can also withstand hail damage, though larger hailstones can still cause dents.

    Wind: A Powerful Force

    High winds can cause significant damage to roofs, especially when combined with rain or snow. Strong winds can tear off shingles, damage flashing, and even lift entire roofs. The NBCC specifies design wind loads for different regions, ensuring roofs can withstand expected wind forces.

    Regional Considerations:

    • Atlantic Canada: This region is prone to powerful coastal winds and hurricanes. Metal roofs or concrete tiles are good options for their durability in high winds. Building codes in these areas may have specific requirements for roof anchoring and wind resistance.
    • Prairies: These regions experience high winds, which can be particularly damaging during hailstorms. Metal roofs or impact-resistant shingles are good options for these areas.

    Proactive Maintenance: The Key to Longevity

    Regardless of your region, regular roof maintenance is vital to extend its lifespan and prevent weather-related damage. Here are some key tips:

    • Schedule annual inspections with a qualified roof inspector to identify potential problems early on, such as missing or damaged shingles, loose flashing, and signs of wear. Early detection allows for timely repairs and prevents minor issues from escalating into major issues. The National Roofing Contractors Association recommends biannual inspections, in spring and fall.
    • Clean gutters regularly, as clogged gutters are a major contributor to roof leaks. Aim to clean your gutters twice a year, once in the spring and again in the fall. This will ensure proper drainage of rainwater and prevent water pooling around your foundation. For homes in heavily wooded areas, more frequent cleaning may be necessary.
    • Trim overhanging branches to minimize the risk of damage from scraping and debris accumulation. Regularly trim back tree branches that overhang your roof. Experts recommend maintaining at least 10 feet of clearance between tree branches and your roof.
    • Address moss growth to prevent moisture and mould issues. Moss buildup on your roof can trap moisture and create a breeding ground for mould. If you notice moss growth, have it removed by a professional roof cleaner. There are also moss-prevention treatments available that can help prevent future growth. Zinc or copper strips installed near the roof's peak can also inhibit moss growth.

    Consider additional protective measures depending on your region and roof type:

    • Roof Snow Removal: In areas with heavy snowfall, consider hiring a professional roof snow removal service to prevent excessive weight accumulation. The Occupational Safety and Health Administration (OSHA) advises against homeowners attempting to remove snow from their roofs due to the risk of falls and other injuries.
    • Attic Ventilation: Proper ventilation in your attic helps regulate temperature and moisture levels, preventing ice dam formation and promoting shingle longevity. Ensure your attic has adequate soffit vents and ridge vents. The general rule of thumb is 1 square foot of ventilation for every 300 square feet of attic space.

    When to Call a Professional

    While regular maintenance can help prevent most weather-related roof damage, some situations require professional intervention. Here are some signs that indicate it's time to call a roofer:

    • Visible Leaks: If you notice water stains on your ceiling or walls, it's a clear indication of a leak in your roof. Don't delay in calling a professional to address the issue. Even small leaks can lead to significant damage over time, including mould growth and structural issues.
    • Missing or Damaged Shingles: Missing or damaged shingles expose the underlying roof deck to the elements. Replace missing shingles promptly and address any damaged ones to prevent further deterioration. After severe weather events, it's wise to have a professional inspection to identify any damage that may not be visible from the ground.
    • Sagging Roofline: A sagging roofline indicates structural problems that require immediate attention from a qualified roofer. This could be due to water damage, inadequate support or excessive snow load in winter regions.
    • Granules in the Gutters: If you notice an excessive amount of granules (the sandpaper-like substance on asphalt shingles) in your gutters, it's a sign that your shingles are deteriorating. This is especially common in older roofs or those exposed to intense sun and heat.
    • Daylight Through the Roof Boards: If you can see daylight coming through the roof boards in your attic, it's a sign of serious roof damage that needs immediate attention. This allows water to enter your home freely during rain events.

    Conclusion

    Your roof is a significant investment, and taking steps to protect it from the elements is crucial. Regional variations in weather patterns and building codes play a significant role in determining the best roofing practices for your area. Consult with local roofing professionals who are familiar with the specific challenges in your region to develop a tailored approach to roof maintenance and protection. Investing in quality materials, regular maintenance, and timely repairs may seem costly in the short term, but it can save you significant money in the long run.

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