Effective snow fences and/or tree windbreaks or shelterbelts for farmsteads and agricultural buildings can help prevent excessive snow on building roofs in future years. Some of the failed roofs in the past either had no protection for the buildings or were located too close to shelterbelts/windbreaks. In either case, it resulted in large snow drifts on top of these buildings. It would seem that producers, builders and farmstead planners are forgetting how important it is to protect farm sites from blowing and drifting snow.
When placing a snow fence or tree windbreak, remember the protected area downwind will generally be 10 to 15 times the height of the shelterbelt or fence. Research in Canada has shown that an 80 percent solid fence (if 1 x 10-inch boards are used you would vertically space them 2.5 inches apart or with 1 x 8-inch boards the spacing would be 2 inches) distributes the snow more evenly and gives better protection downwind than a solid fence. As an example, a 12-foot high windbreak fence (80 percent solid) will protect from 120 to 180 feet downwind. Also, most of the snow will drop within the first 30 to 40 feet immediately downwind of the fence/trees or roughly within the first 25 percent of the protected area. When locating a machine shed or livestock building downwind from a shelterbelt, leaving an area or space for snow to accumulate is very important. If the building is too close, it will be within this snow drop area, and if too far from the windbreak, it will be outside of the wind protection zone.
Hopefully, March 2014 will provide some opportunity for accumulated ice and snow on roofs to melt or slide off. But if we receive even normal amounts of snow during the remainder of this winter accompanied with cold temperatures, you should monitor the snow load situation on agricultural buildings and take appropriate action. Check high-risk areas, and be extremely careful if you need to remove snow.