Snow load engineering protects your building investment

Name: Summit Steel Buildings
Address: 22420 Dewdney Trunk Road, Maple Ridge, BC, CA
Telephone: 877-417-8335

Frank Melo • December 9, 2025

Rely on Summit Steel Buildings’ experience when it comes to supplying commercial structures specifically designed for northern climates. Get the precise engineering designed to handle heavy snowfalls.

Written by Frank Melo

For companies operating across Canada and the northern United States, winter is not just a season – it is a challenge for engineering design to handle structural loads. Clients frequently come to Summit Steel Buildings seeking reassurance that their new facility will perform reliably under heavy snowfall, freezing temperatures and constant thermal cycling. Snow load capacity is one of the most critical factors in designing any pre-engineered steel building, because snow is uniquely hazardous: it is heavy, unpredictable, capable of drifting into deep accumulations, and it significantly impacts a building’s thermal and structural behaviour.

According to the National Research Council of Canada and the American Society of Civil Engineers’ Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE 7-22), snow loads remain one of the primary drivers of roof design, material selection and safety considerations for industrial and commercial structures. In regions with extreme winters, engineering a building without rigorous attention to snow load is not an option – it's a necessity.

Occupancy and building use are critically important

Building use significantly affects the thermal and structural design approach used in the design and construction of every Summit Steel Buildings project. The type of building use is important to know. Two broadly classified building uses exist: heated structures used by people throughout the year for operations versus those simply used to store equipment. Both conditions require tailored insulation values, roof compositions and snow load calculations to meet code and ensure long-term resilience.

Roof design and insulation has a huge impact on how snow builds up and potentially melts:

Heated, operational facilities (manufacturing plants, sports complexes, retail spaces) naturally warm the roof surface from below. Snow partly melts and settles, lowering the thermal coefficient; this requires precise insulation and vapor control design to avoid ice damming.
Unheated storage facilities (golf cart barns, boat storage, equipment shelters, non-perishable inventories) lack internal heat gain, meaning snow remains cold, dry, and heavy. Engineers must assume maximum accumulation and design for higher load factors accordingly.

Understanding why snow load and thermal exposure matter

Snow load and exposure classification guide Summit Steel Buildings’ engineers in determining the building’s thermal coefficient, an adjustment factor that accounts for insulation levels, heat loss and expected roof surface temperature. A well-engineered envelope helps stabilize the building’s interior environment while reducing the risk of structural overstress.

Ground snow load serves as the foundational metric from which roof snow loads are derived. The values are based on decades of meteorological research on regional snowfall, density and drift patterns published by NBCC Climatic Data Tables (Canada) and ASCE 7 (United States). Summit Steel Buildings relies on this data to help guide their engineering design to ensure buildings are designed to exceed code wherever they are installed.

However, the company’s engineering does not end there. Several critical design features help mitigate the risk that accumulated snow poses to roofs. Summit Steel Buildings’ leadership team incorporates key structural design factors to help reduce snow load risk:

Structurally strong roof systems – Heavy steel framing, engineered purlins and load-optimized moment connections ensure the roof can support both balanced and unbalanced snow loads. High-quality pre-engineered systems distribute loads efficiently while maintaining structural redundancy.
Roof slope and geometry – Steeper slopes facilitate snow shedding, while properly engineered drainage ensures snow loads are transferred safely to grade. ASCE and NBCC research confirms that slope adjustment factors can substantially reduce the effective snow load carried by a roof. Learn more about roof shape and design.
Thermal behaviour and insulation strategy – Snow accumulation interacts with heat transfer through the roof assembly. Heated buildings lose upward heat that may partially melt snow, decreasing load but increasing the potential for ice dam formation if not managed correctly. Cold, unheated structures retain more snow, requiring higher calculated thermal coefficients.

This often-overlooked thermal analysis is essential for predicting both snow load retention and winter energy performance.

How engineers calculate roof snow loads
Roof snow load is influenced by several environmental and structural variables shared by ASCE 7 and NBCC principles:

1. Snow exposure co-efficient
Exposure affects how snow accumulates – or blows off – a roof.

Fully exposed: Open terrain allows wind scouring and reduces snow retention.
Partially exposed: Most common condition; neither sheltered nor exposed.
Sheltered: Surrounded by trees or buildings, resulting in significantly higher retained snow.

2. Terrain category
Terrain roughness influences wind speed and snow transport:

Urban and suburban areas with repeated obstructions.
Open terrain with scattered low obstacles.
Flat, unobstructed plains or water surfaces.

3. Roof geometry and heat transfer
Mechanical equipment, parapets and roof steps interrupt natural wind flow and collect snow; these elements must be included in the load analysis.

Hidden threats: Unbalanced and drifting snow

Unbalanced snow loads occur when roof geometry – particularly gable and multi-level structures – causes uneven accumulation. One roof plane may experience significantly higher load than the other, especially during windy storms.

Snow drifting is also a major design factor. Drifts commonly form:

At changes in roof elevation
Against parapets
Between building sections with different eave heights
Downwind of roof obstructions

These localized loads can exceed uniform snow loads severalfold. Summit Steel Buildings’ engineering is used to model drift height, density and shape to ensure the structure resists localized overstress.

Ready to build for winter? Complete your project with the right engineering partner
Designing for snow loads is complex. It requires a sophisticated engineering process with a deep understanding of regional climatic data, building use, exposure class, roof geometry and thermal conditions. By integrating these factors, Summit Steel Buildings ensures that every pre-engineered steel building is optimized for winter performance – safe, resilient and cost-effective.

Whether your facility must withstand the lake-effect storms of Ontario, the heavy snow packs of the Rockies or the freeze-thaw cycles of northern U.S. states, Summit Steel Buildings can deliver an ideal, safe and resilient pre-engineered building solution specifically engineered for your exact geography and snow conditions.

Contact Summit Steel Buildings to discuss your building plans with our team. We’ll provide you with preliminary technical drawings and a cost-effective price to support business growth. Reach our team online, by email at info@summitsteelbuildings.com or at 877-417-8335.

About the author

Frank Melo has a construction civil engineering technology and business background with over 30 years of experience as a business owner and contractor. He was raised and educated in London, Ontario and now divides his time between projects primarily in Ontario, British Columbia and Washington State. He can be contacted at Summit Steel Buildings at (778) 951-4766 or by email at frank.melo@summitsteelbuildings.com or through LinkedIn.