Tag: roof straitions

Roofing and Snow: Everything You Need to Know – Part Two

Posted on by Ken Buchinger

Additional considerations for working with metal panels in winter.

In part one of our series on metal roofing and snow, we covered five of the most important elements to consider when preparing structures for winter weather. In this post, we’ll review four more ways to prevent unexpected, costly damage of metal panels in winter.

  1. Consider roof material and surface color

Metal roofs absorb heat quickly and radiate it effectively. Darker panel colors can enhance this solar absorption effect, which can save you money year-round. But because UV light can pass through 3-5 inches of snow, when combined with heat loss through the roof, it becomes more difficult for snow to stay solid. To minimize the chance of ice damming, you should ensure your roof system is properly sealed and insulated. If not, ice damming may occur and the melting and re-freezing of snow throughout the day can result in icy layers that promote snow sliding—no matter the roof material or color.

  1. Review weathertightness factors

For low-sloped roofs (less than 3:12), it is especially important for panel seams to be watertight to prevent water (melted snow) from leaking into the structure. This can be problematic when snow gathers and stays on a roof. Architects, designers and specifiers, therefore, should consider using panels that have passed the ASTM 2140 water head test or FM 4471 Appendix G water test. Water-resistant underlayment should also be considered for all roof slopes.

ABC Blog: Roofing and Snow: Everything You Need to Know about Metal Panels in Winter - Part Two
A close-up of this dormer roof illustrates how the impact of sliding ice and snow can damage panel seams.
  1. Consider your roof layout

Design elements like valleys and slope changes cause snow to collect and increases your snow load. Also, when dormers extend from a large roof area and one area is significantly bigger than the other, the structure is susceptible to experiencing unbalanced sliding snow. This imbalance can actually tear open standing seams and displace panels. Also consider that drifting snow may accumulate behind HVAC units, at perimeter walls, and behind solar and photovoltaic (PV) panels.

  1. Ensure Proper Roof Maintenance

One of the best ways to prevent snow and ice issues is to regularly inspect and maintain your roof. In addition to cleaning and inspecting your roof for possible issues, properly removing standing snow and preventing ice dams is a vital part of avoiding damage to your metal panels in winter. This often requires that you get into your attic to inspect for air leaks—the leading cause of ice dams. Read more about how to properly maintain and remove snow from your roof in this blog post.

If an issue is discovered, consult your roofing material manufacturer for recommendations as well as advice on warranty claims. Additionally, you can reach out to a trusted roofing professional in your area. These professionals can thoroughly inspect your roof system to help you determine ways to rectify any potential issues. You’ll want to do this before damage and/or injury occurs and before you pay for sub-par or ineffective repairs.

If you missed part one of this series, click here for our top five considerations. These include managing snow load and sliding snow, preventing ice dams, using retention systems and more! For more information on how metal panels fare in winter weather conditions and for advice on how to winter-proof your roof, reach out to an ABC representative today.

Roofing and Snow: Everything You Need to Know – Part One

Posted on by Ken Buchinger

What to consider when designing and building in snow-prone areas.

While properly-designed metal roofs historically perform well in winter, heavy snowfall can be detrimental to buildings of all kinds. Those who live and work in and around them are also at risk when snow and ice cause dangerous situations. Even though winter doesn’t formally begin until late December, colder weather is upon us. And while you might not be expecting snow or ice yet, keep these roofing and snow tips in mind when designing, constructing and maintaining structures in areas where there’s a chance for snow and/or ice over the course of the year.

Considerations for Snow-Bearing Roofs:

  1. Anticipate Snow Load

Snow accumulates on every roof type, and as this happens, it increases the amount of weight your structure is bearing. This increased weight (snow load) can pose several threats to the structure and those in and around it. For example, when the weight of snow or ponded water from melted snow exceeds the structure’s limits, the roof or even the entire structure can collapse. Be sure you’re aware of the weight your structure can bear and remove snow to keep it within its limits. Consult the International Building Code (IBC) as well as state and local codes for guidance based on your location.

  1. Prevent Ice Dams

Most ice dams are the result of air barrier flaws in buildings. If warm indoor air escapes through the roof floor, it warms the roof sheathing and melts the underside of the layer of snow on top. This water then moves down the slope of the roof toward the eaves, where it freezes into ice. As this process continues, the ice gets thicker and thicker, resulting in ice dams. The presence of these dams allow water to back up and form a reservoir that can cause major damage.

To prevent ice dams, you should:

  • Seal all air leaks at the attic floor
  • Ensure proper insulation
  • Provide adequate attic ventilation

Another tip is to use a peel and stick membrane on the roof deck extending from the eave to about 3’ up-slope from the exterior wall. For more specific details on the ice dam prevention tips above, read our recent blog post.

  1. Prevent Sliding Snow

Gravity can cause accumulated snow to slide down the roof’s slope (shedding), potentially injuring people and damaging property below. Despite this, snow shedding must occur to keep the snow load from accumulating beyond the buildings structural limits. Balancing snow load and shedding is important and requires that you consider geographical and building material and roof design factors.

ABC Roofing and Snow Blog
Ice and snow sliding down the main roof has damaged the roof panels and the valley trim on this connector roof.

Roof slopes of 45 degrees (12:12) or more, can accelerate sliding snow with sometimes immense and dangerous consequences. For example, if snow accumulates and then falls onto an exterior gas line, pipes could rupture. From there, the smallest of ignition sources could set the structure ablaze. In addition, the weight of sliding snow can propel any icicles formed on eaves can be propelled down by the force and weight of sliding snow onto people and property below.

On slopes less than 45 degrees (6:12 to 9:12), low amounts of friction (like on smooth roof surfaces) means it offers less resistance to sliding. Striations and embossing on roofing materials like metal panels add a small 3D profile and improve the resistance to sliding, especially when they run traverse to the slope.

This can get complicated, but in general, installing metal panels with snow retention devices on a steeply-sloped roof is recommended. This approach will naturally shed snow and ice, and protect your structure from excessive snow loads. If you have a low-sloped roof, be sure it’s design supports snow as shedding won’t occur naturally. Including enough snow retention devices from ridge to eave is also imperative for this design.

  1. Use Retention Systems

A variety of retention options, such as snow fences, bars or guards, are designed to make snow and ice melt completely or fall from roofs in small amounts. This helps reduce risks associated with sudden rooftop avalanches while maintaining the clean lines of the roof. It is important that snow retention systems are carefully engineered and properly installed. Models like S-5!’s snow-retention device design resource allow you to input your roof dimensions and expected snow load to adequately engineer snow fence assemblies.

  1. Protect Roof Attachments
ABC Roofing and Snow Blog_Pipe Protection
This pipe penetration is protected from sliding ice and snow by a small section of S-5! ColorGuard to the panel seams immediately up-slope from the pipe.

The weight of sliding snow can be powerful enough to take off attachments like exhaust vents. To combat this, reduce the shear load by installing rigid vent pipes securely and as high up on the roof slope as possible. If this is not possible, protect the pipes with a snow retention system.

While metal roofing responds well to harsh winter weather, it is imperative to take the time to keep snow, ice and moisture from causing issues. No matter the roofing design or material used, keeping people and property safe from overhead dangers should be a priority when designing, installing and maintain your structure.

In part two of this roofing and snow series, we’ll review additional considerations. It contains tips on roof layout, color, weathertightness and maintenance, which also play important roles in winter weather protection.

For more information on roofing and snow like how metal panels fare in winter weather conditions and for advice on how to winter-proof your roof, reach out to an ABC representative today.