Building to Last in the Western Mountain Region
by Andy Ankeny AIA, principal at CLB
(Editor’s Note: As a native of the West, Andy Ankeny designs buildings that are inherently simple and cohesive, honoring the area’s vernacular architecture with a modern sense of scale and proportion. He is inspired by the relationship between built forms and their natural surroundings, and believes that good architecture is inseparable from and enhances a sense of place. Now a partner, Ankeny joined CLB in 2000 after earning his Master of Architecture Degree from Montana State University.)
Architecture is inseparable from the land on which it rests. As a native of Jackson, Wyoming, I am particularly attuned to the effects of climate on buildings, and the manifold considerations that must be taken into account to provide structurally sound homes in extreme environments. We find that many firms struggle to build in the Western Mountain Region because of its distinct seasonal challenges. For architects to be successful in these kinds of cold climates, they need to be forward-thinking about the level of engineering such conditions necessitate.
Critics may call it over-engineering, but a failure to be proactive in addressing climate concerns can lead to significant consequences. Simply adhering to code minimums for new buildings can create problems down the line such as structural failures, ice dams, roof leaks, lack of ventilation, and mold. The issues faced by Western communities go far beyond the abundance of snow and snowmelt. Wyoming sees temperature swings of up to 60º in a single day, creating structural stressors through thermal expansion and contraction. The increased UV radiation that accompanies higher altitudes likewise creates opportunities for material and structural deterioration. Greater seismic activity in the West will also negatively impact buildings that are less structurally sound. Architects working in this kind of climate cannot afford to follow the same rules that apply in milder environments.
With so many concerns surrounding cold-climate design, roof design is one of the primary considerations in the West, and it is critical to take snow retention into account. Wyoming sees some of the heaviest snowfalls in the country, and roof buildup can reach up to 8’. Snow slides and falling icicles from roofs carry the potential for injury and property damage. Roofs that require consistent shoveling will see much quicker rates of degradation. We take care to engineer our roofs to withstand high snow loads. This ensures the integrity of the structure so that it does not deflect beneath the weight, and also prevents cracking of interior drywall and window damage. Simplified roof forms are often used in response to snow, as well as for style. Some of the biggest structural issues we see, such as ice damming and leaking, result from overly complex roof forms that fail to account for the climate. One simple roof form often used in the West is the snow shed roof, which is designed to enable snow to slip from the roof rather than build up.
The structure of a roof and how it handles snow comes down to an exact science. Below a pitch of 5:12, roofs will hold snow, and above it, roofs will slide or shed large accumulations. The exception to this rule is a roof made of metal, off of which snow will slide at all slopes. However, not all snow density is the same. Freshly fallen powder snow at 5% water content weighs 3 lbs. per cubic foot, whereas fully saturated snow at 32% water content weighs 21 lbs. per cubic foot. We take all of this into account, with the ultimate goal of ensuring that our clients will never need to shovel their roofs.
The careful selection of materials is another consideration that cold-climate designers must take into account. Higher UV levels will break down materials such as sealants, caulks, and rubber much more quickly than in milder climates. For this reason, we select materials that are long-lasting, but also low maintenance. Buildings clad in steel or concrete, rather than paints and stains, are much more durable in the face of solar exposure. Buildings composed of these materials are also more structurally capable of withstanding thermal changes and seismic activity.
The durability of materials and structures is a critical component of sustainable design, which is something we place great importance on at CLB. Sustainability in design means more than building with renewable materials or alternative energy systems. Architecture that is built to last is the most sustainable kind of design. We see many homes in our area that are not built for longevity, and will inevitably be torn down and rebuilt. At CLB, our goal is to build structures that will last 100 years or more. This ties not only into the careful engineering and selection of materials required in the harsh Western climate, but also into the timelessness of our designs. Homes that rely heavily on current design trends are the first to be torn down. When a design is timeless and inspired by its surroundings, it endures.