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02.02.16

Designing For Extremes: Snow & Ice

Coming off the heels of a truly epic storm for the Washington D.C. area (and most of the east coast!), I thought I’d take a moment to address how design techniques can help barns “weather” extremes.

In the United States, the upper northeast regions through to the Midwest are prone to experience weather extremes in the form of snow and ice. While we cannot entirely “weather proof” a barn, we can make it more resilient to some of the more damaging effects of weather phenomena.

Barn In A Blizzard

The roof of your barn needs to be able to:

  • Withstand the weight of snow and/or effectively shed it
  • Prevent or reduce the formation of ice dams
  • Redirect “roof avalanches” from sliding into high traffic or poor drainage areas and also reduce associated noise that could frighten the horses.

In addition to contributing to the Bernoulli principle I incorporate for natural ventilation, steeply pitched roofs also contribute to effective, gradual roof shedding and the redistribution of snow load. Ideally the pitch should be between 4/12 and 6/12 to get the optimal shedding effect (although, we generally try to keep pitches at 7/12 or more to take full advantage of the Chimney Effect and Bernoulli principle for natural ventilation)

Roofing material will also factor into how the snow will shed. Metal roofs are excellent as they are smooth and slick. They will also stay colder longer; reducing the likelihood that snow will melt and form ice dams (more on this below). Snow will shed from a metal roof even if the pitch is lower. Shingled roofs, however, will slow down the shedding process by “holding on” to the snow and allowing it to stay in place and accumulate. Consider a steeper pitch if you prefer a shingled roof as it will facilitate the shedding process over the rougher material.

Winley - Roof

Winley Farm – Millbrook, NY

 

Now, you might be saying to yourself, “Well, the snow is off the roof…but it’s all over the place! Now what?” Including strategic roof overhangs will complement the steeper pitch by helping to distribute shedding snow away from exterior walls and out of traffic and poor drainage areas. Be wary though, snow sliding off roofs can be noisy and frightening to horses, not to mention dangerous if it falls on you! Snow guards on the roof can help reduce the noise associated with shedding snow and keep huge sheets of it from falling on (and potentially harming) 2 and 4 legged passersby. Gabled dormers over entryways can also be useful. They help to direct snow off to the sides.

Beechwood Stables - Weston, MA

Beechwood Stables – Weston, MA

Snow guard

Snow guard

Ice dams are another unfortunate side effect of snow-laden roofs. An ice dam forms when the underside of the roof gets warm enough to thaw the bottom layer of snow sitting on the other side. The water makes its way down to the eave where it refreezes, eventually growing into a mound of ice. As the ice dam gets larger, it can pull the shingles and edges up allowing water to get through and into the insulation and walls. Water damage then wreaks havoc on the interior of the barn. The ice dam could also break off the eave and take pieces of the roof with it or fall on passersby. Sure, there are ways to deal with ice dams once they’ve formed, but natural ventilation can help prevent them upfront. Natural ventilation keeps the underside of the roof within 10 degrees of the outside temperature, which aides in keeping that critical layer of snow right on top from thawing and running down towards the eaves.

Damn ice

Damn ice

ice-dam-roof-graphic-a4who

Site and circulation planning can help prevent and/or reduce the impact of icy conditions around equine walkways. In the interest of horse safety, I try to design site circulation so that horses do not need to move over asphalted areas intended for trucks and service vehicles (there are other benefits associated with that as well). Asphalt is not great for horse’s knees, generally, but it is particularly problematic when wintery conditions lead to the formation of “black ice” — a thin sheet of ice over the asphalt that can be imperceptible to the horse or persons walking on to it. Horse pathways in and around the barn should include porous footing that absorbs and carries moisture away quickly. Presently there is no way (that I know of) to prevent pastures from freezing over, but you can maintain a dry paddock or “sacrifice” lot where your horses can be turned out when pastures have been effected by inclement weather. Paddocks with considerable slope can be particularly hazardous when they freeze over. That’s when a “level” dry lot can be very useful!

ice-storm-dec-16-2010-055

Caution!

 

As many on the east coast found out this past week, there is only so much preparation you can do in a couple of days before a storm hits. You, your horses, and your barn will benefit from built in preparation.

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