A flat roofing system provides several functional advantages and is durable throughout most of the year. However, during the chillier months when it starts to snow, your roof can experience issues.
Unlike pitched roofs, which allow snow to slide off, flat roofs hold onto the weight—and that weight can pile up fast. If you’re a homeowner or business owner with a flat roof, understanding how much snow your roof can safely hold isn’t just helpful—it’s essential.
We’ll break this down step-by-step in our guide, addressing key concerns, explaining terms in plain language, and providing actionable advice. Let’s get started!
Why Does Snow Load Matter On A Flat Roof?
You might be thinking, how can the beautiful, white snowfall of Western New York damage my flat roof? Unfortunately, there are many ways the winter weather can harm your flat roofing system.
Snow might look fluffy and light when it’s falling, but it can pack a punch when it settles on your roof. A heavy snow load can strain your roof structure, leading to sagging, leaks, or even collapse in extreme cases.
Though snowfall affects both pitched and flat roofing systems, it is the latter that you need to worry about more.
As a building owner or manager, you should know that a snow-laden flat commercial roof isn’t just a structural hazard—it can interrupt operations, damage inventory, and create liability issues.
A pitched roof has natural slopes that help snow slide off more easily, distributing the weight and reducing the potential for excessive accumulation. Flat roofs, by contrast, lack this inherent drainage mechanism, making them particularly vulnerable to snow buildup. The horizontal surface of a flat roof allows snow to settle and compress, creating a dense, heavy layer that can exert significant stress on the building’s structural integrity.
Factors Affecting How Much Snow Your Roof Can Hold
The pitch of your roof is a big factor in how much snow it can hold. However, several other factors contribute:
Snow Density
Not all snow weighs the same. The density of the snow significantly affects the weight on your roof:
- Fresh, fluffy snow: Approximately 5 pounds per cubic foot.
- Compacted or wet snow: Can weigh 20 pounds per cubic foot or more.
- Ice layers: The heaviest, at around 58 pounds per cubic foot.
For instance, a foot of fluffy snow might not be a problem, but a few inches of dense, wet snow or ice can put your roof under significant strain. That’s why it’s important to consider both the type and depth of snow accumulating on your roof.
Water Drainage and Ponding
Flat roofs are especially prone to drainage issues. If snow melts unevenly or the roof’s drainage system is obstructed, water can collect on the surface, creating additional weight and stress. This issue, known as ponding, can lead to leaks, sagging, or even structural damage over time.
To prevent these problems:
- Inspect your roof regularly, especially after heavy snowfall.
- Ensure all drains, scuppers, and gutters are clear and functioning properly.
- Watch for signs of ice dams, which can block drainage and worsen the problem.
Signs Your Flat Roof Is Overloaded
Excessive snow accumulation on a flat roof can lead to significant structural stress. Recognizing the warning signs early is crucial to prevent damage or a potential roof collapse. Let’s delve deeper into these red flags:
Sagging Roof
If you notice your roof or ceiling beginning to sag, it’s a clear indication of structural stress caused by excessive weight. Sagging often starts subtly, with beams or ceiling tiles slightly bowing, and can escalate quickly if ignored. Regularly inspect your roofline from both inside and outside for any unusual dips or deflections. Early detection can prevent catastrophic failure and save you from costly repairs.
Heavy Snow Can Cause Roof Leaks
Water stains or active dripping inside your property suggest that the roof is struggling to handle the snow load. Leaks occur when the pressure forces cracks or gaps in the roofing material, allowing melted snow to seep through. These leaks not only damage your property but can lead to mold growth and compromise the roof’s structural integrity. Always investigate stains on walls or ceilings promptly, as they often indicate deeper issues with the roof.
Creaking or Popping Sounds
Strange noises coming from the attic, such as creaking or popping, can signal that the roof is under intense strain. These sounds occur when the materials in the roof, such as beams or trusses, are flexing or shifting under pressure. While occasional noises might be normal in cold weather due to thermal expansion, persistent or loud sounds are a warning that immediate action is needed to alleviate the load.
Doors and Windows Sticking
If your doors and windows suddenly become hard to open or close, it might not just be a problem with the frames. Excess weight on the roof can cause the entire structure of your building to shift or settle unevenly. This misalignment affects how doors and windows function and can be a sign of significant stress on the building’s frame. If you notice this issue, consider it an urgent cue to inspect your roof.
Ice Dams
Ice dams are a phenomenon that is more associated with pitched roofing systems. While flat roofs are less likely to experience traditional ice dams due to their lack of slope, water pooling from uneven snow melt can freeze and create similar blockages on flat roofs. So keep an eye out for that.
Also Read: Winter Warning: Ice Dams On The Roof And How To Prevent Them
How to Calculate Snow Load on Your Roof?
Want to estimate how much snow is on your flat roof? Here’s a simple formula:
- Measure the depth of the snow (in feet).
- Determine the snow type (fluffy, wet, or icy) and its approximate weight per cubic foot.
- Multiply the depth by the weight.
For example:
- 2 feet of fluffy snow at 5 pounds per cubic foot = 10 pounds per square foot.
- 1 foot of wet snow at 20 pounds per cubic foot = 20 pounds per square foot.
Compare this number to your roof’s load capacity to determine if action is needed.
When to Call Our Professional Roofers In Western New York
Let’s face it—roof maintenance isn’t everyone’s idea of fun. And if you’re dealing with heavy snow or suspect your roof is at risk, it’s always better to call a professional roofing company like Buffalo’s Best Roofing Company LLC.
Here’s when to pick up the phone:
- There has been heavy snowfall.
- You see signs of structural stress (sagging, leaks, etc.).
- The snowfall has exceeded 20 pounds per cubic foot and feels unsafe or overwhelming.
- You want a thorough inspection to assess your roof’s condition.
As a prominent roofing company serving Western New York, we have the expertise and equipment to handle snow loads safely and effectively. Whether you’re a homeowner or a business owner, we’re here to help keep your flat roof in top shape. Contact us today at (716) 276-3673 to know more.