Weather Worries
Designing Steep Slope Roofs for Cold & Snow Regions
by Richard K. Olson, President & Technical Director, Tile Roofing Industry Alliance
(Editor’s Note: Richard K. Olson is president and technical director for the Tile Roofing Industry Alliance. The association represents industry professionals involved in the manufacturing and installation of concrete and clay tile roofs in the United States and Canada, and works with national, state, and local building officials to develop installation techniques, codes, and standards for better roofing systems. Olson can be reached at rolson@tileroofing.org.)
Steep slope roofs in cold and snowy regions present unique challenges and opportunities for designers and roofing professionals. While much of the world’s building practices aim to retain snow on roofs for its insulative properties, in the United States, the focus is often on snow removal. This contrasting approach underscores the importance of understanding local climate, codes, and best practices when designing for these environments. By addressing these factors, builders and designers can create roofs that perform efficiently and withstand even the harshest winters.
Global & Regional Approaches to Snow Retention
In many parts of the world, retaining snow on roofs is a common practice. The snow layer acts as a natural insulator, reducing heat loss and improving energy efficiency. Additionally, this approach eliminates the need for designated snow drop zones, which can pose safety hazards if not properly managed. However, in the United States, the emphasis is often on removing snow from roofs, either through natural shedding or mechanical means. This divergence in practice highlights the need for region-specific design considerations.
Understanding Local Codes & Conditions
Effective roof design begins with a thorough analysis of local weather patterns. Key factors roofing professionals may wish to consider include: ice dam formation potential, temperature variations, solar exposure, and checking in with your local building official.
Proximity to geographical features such as warm bodies of water or mountains can also influence local microclimates, affecting snow and wind patterns. These areas tend to see greater snow accumulations and will need designs for higher snow loads. In these areas we tend to see greater ice damming challenges and safety concerns.
Common Design Pitfalls
While simplicity is often an asset in roof design, overly simplistic approaches can neglect critical considerations such as snow movement patterns and load distribution. For example, designing roofs without adequate overhangs or slopes can lead to snow buildup near walls, increasing the risk of leaks and structural damage.
A lack of balanced ventilation can result in uneven snow melting, exacerbating ice dam formation. This issue can compromise the roof’s integrity over time. Cold roof installations aim to keep the roof surface at or below the outside air temperature to prevent snowmelt. Without proper insulation and ventilation, the design can fail, leading to ice dams and water damage.
Chimneys, vents, and other roof protrusions can disrupt snow flow and create areas where ice and snow accumulate. Strategic placement and appropriate flashing are essential to mitigate these risks. When snow or ice slips downslope, they can bend or break vent stacks, skylights, and other penetrations.
Structural engineering must account for snow loads, wind loads, and the combined stresses they impose on the roof. Local codes often specify minimum requirements, but exceeding these standards can enhance durability and safety.
Design Upgrades for Improved Performance
For concrete and clay roofing tile, installing with elevated, raised, or counter batten systems improves ventilation and minimizes ice dam risks by allowing air to circulate freely beneath the roofing material. It will also provide an energy reduction by creating a natural above sheathing ventilation, which acts as a barrier for heat transmission in both hot and cold climates.
Upgrading to high quality underlayment’s can provide better resistance to ice and water infiltration. These materials are designed to perform under extreme conditions, making them a wise investment in cold and snowy regions.
Snow retention systems tailored to the specific climate and site conditions can prevent sudden snow shedding and distribute snow loads more evenly. Options include snow guards, fences, and
bar systems, which can be integrated seamlessly into the roof design.
Improved eave treatments, such as self-adhering underlayment’s and reinforced flashing, protect vulnerable areas of the roof. These enhancements are crucial for managing ice dams and ensuring long-term durability and maximum performance.
Designing steep slope roofs for cold and snowy regions requires a nuanced approach that balances local climate conditions, building codes, and advanced engineering solutions. By leveraging resources like our TRI Alliance’s guide and incorporating climate specific considerations, builders and designers can create roofs that not only withstand harsh winters but also enhance energy efficiency and occupant safety. With thoughtful planning and attention to detail, steep slope roofs can provide lasting protection and performance for buildings in cold and snowy regions.
