A preventive measure to avoid excessive snow on building roofs in future years is to have effective snow fences and or tree (shelterbelts) windbreak for farmsteads and/or agricultural buildings. Some of the buildings' roofs that have failed in past years were located either too close to shelterbelts and/or windbreaks or there were no protections for the buildings at all.
When placing a snow fence or tree windbreak, remember that 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 distributes the snow more evenly and gives better protection downwind than a solid fence. (If 1 x 10" boards are used, you would vertically space them 2.5 in. apart or with 1 x 8" boards the spacing would be 2 in.) As an example, a 12-ft. high windbreak fence (80 percent solid) will protect from 120 to 180 ft. downwind. Most of the snow will drop within the first 30 to 40 ft. immediately downwind of the fence/trees or roughly within the first 25 percent of the protected area.
Leaving an area or space for snow to accumulate is very important when locating a machine shed or livestock building downwind from a shelterbelt. 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, the 2012-13 winter will provide some opportunity for the accumulated ice and snow on roofs to melt or slide off, but if we receive above normal snowfalls with cold temperatures, monitor the snow load situation on agricultural buildings and take appropriate action. Check high risks areas and please be extremely careful.
For more information about protecting your home and landscape from winter damage, visit www.extension.umn.edu/extreme-weather and click on "Winter Damage."