The most common mistake when setting up a snow fence is improper placement. To be effective, a snow fence must be positioned correctly and sized according to the local snow and wind conditions.
On the Prairies, winds usually blow from the north or south, so it’s essential to assess how much open space there is in those directions. Typically, a fetch — the distance over which wind carries snow — less than four kilometres doesn’t require extra consideration. In an average winter, the Prairies see about 100 cm of snow, with about 70% of it being blown by the wind unless natural barriers trap it first.
For example, on a cultivated field with a fetch of 500 metres, you could expect around 25 tonnes of snow to be moved per metre throughout the winter. This figure jumps to 100 tonnes per metre for fetches over 3,000 metres. A snow fence needs to handle this volume, or snow will drift beyond it. If placed too close to what you’re protecting, the drift could spill into that area.
The height of a snow fence determines how much snow it can capture. A four-foot fence is enough to handle about 25 tonnes per metre, while for our example of a 3,000-metre fetch, you'd require a fence of around eight feet. Pre-made fences are usually four to five feet tall, but leaving a six-inch gap at the bottom improves efficiency by up to 30%.
In most Prairie regions, a fence 4.5 to 5.5 feet tall will do the job. If needed, you can double up by placing two fences parallel to each other that are spaced using the established guidelines.
A full-size snow drift can extend downwind around 35 times the height of the fence. For a 4.5-foot fence, this means it can produce a drift around 150 feet long at maximum length. The fence should be positioned perpendicular to the prevailing winds and should extend 10 times its height beyond the area you wish to protect. For a 300-foot-wide area, the fence should be 400 feet long, extending 50 feet past each side.