Preparing for Snow Season: Snow Accumulation Prevention and Removal Guidelines for Steel Buildings
As the stormy season approaches, Dalal Steel wants to share important information regarding snow accumulation prevention and removal measures. Snow load, roof pitch, and building design considerations all play crucial roles in determining the safety and structural integrity of a building during heavy snowfall. This article provides valuable insights and guidelines to help you understand and manage the impact of snow on your steel building or prefabricated house.
1. Understanding Snow Load and Density
1.1 Translating Snow Load to Snow Depth:
Determining the exact snow depth that a building can safely support is challenging due to the varying densities of snow. Snow can range from light and fluffy to wet and heavy. Therefore, it is not possible to establish a single value for the allowable height of snow. Additionally, as snow melts due to building heat loss or absorbs water from melting snow above, its density increases. The accumulation of ice beneath snow layers further intensifies the roof loading. Consequently, it is essential to be aware of your roof's design capacity and regularly monitor your building's snow load.
1.2 Typical Densities of Snow and Ice (kg/m3):
- New snow (immediately after falling in calm conditions): 50-70
- Damp new snow: 100-200
- Settled snow: 200-300
- Wind-packed snow: 350-400
- Very wet snow and firn: 700-800
2. Impact of Roof Pitch on Snow Buildup
The roof pitch significantly influences snow accumulation and related issues. High slope roofs (greater than 3:10) can experience snow sliding off easily. In contrast, low to mid-slope roofs (less than 3:10) tend to accumulate snow over time, becoming denser and icier. This is particularly concerning around areas with height variations or vertical surfaces such as parapet walls and equipment. Snowdrifts can become trapped in these locations, leading to concentrated weight that exceeds design specifications. Accumulated snow can also infiltrate flashings, potentially causing water leaks.
3. Snow Removal Procedures
If your building already has a significant amount of snow or ice, it is advisable to reduce the snow load uniformly before an upcoming storm. Rain and additional snowfall can substantially increase the roof loads. Here are some pointers for safe snow removal:
3.1 Clearing Snow without Roof Damage:
- Inspect the roof system visually to identify any unusual deflections of frames, purlins, or joists. Begin by removing approximately half of the snow depth in areas that won't cause unbalanced loading conditions on the frames or purlins.
- Identify areas that require immediate roof bracing or additional support for unaccounted loads, whether suspended or from the exterior.
- Start shoveling from each endwall towards the center, progressing in larger roof areas with additional people working from the center to the ends.
- Remove drifted areas first to bring them down to the same level as the rest of the snow. For instance, trim drifts of 1m deep to 0.5m before proceeding.
- Clear snow from the eave towards the ridge, sliding it off the roof over the gutter.
- Remove snow from the middle one-third of each bay across the full width of the building, starting with the most densely packed bay. Complete snow removal on the remainder of the building.
- On gable buildings, simultaneously remove snow from both sides of the ridge.
- Eliminate excessive snow depth using the same method as described above.
- Avoid using metal shovels or scraping the roof down to the surface of the panel. The objective is to relieve the excess loading condition caused by snow weight, not to completely clear the roof of snow
Key Takeaways: Snow Accumulation Prevention and Roof Maintenance for Steel Buildings
Safeguarding Your Steel Building Against Snow Accumulation" to summarize the key points discussed in the article and provide a final takeaway for your readers.
