Swine & U

We’ve had some snow this winter, and in most cases folks have found a place to put it all. In the event that we find ourselves in the midst of heavy snows, it’s good to have a plan to prepare for snow effects on farm buildings and to know and plan for where it will go when it melts.

University of Minnesota engineers Chuck Clanton, Erin Cortus, Kevin Janni and Extension specialist Krishona Martinson collaborated to help farmers address snow handling issues on the buildings and in the barnyard. Their assessments and advice are found below.

Snow loads on the roof

The excessive amount of ice and snow this past month has livestock owners concerned about snow load and potential roof collapse. The design roof snow load for residential buildings in Minnesota is set by state statutes and is 42 pounds per square foot in northern Minnesota and 35 pounds/sq. foot in southern Minnesota. However, many agricultural buildings are built using a 20 pounds/sq. foot snow load which would be expected to handle six feet of dry, fluffy snow or one foot of wet, heavy snow.

Estimating the weight of snow and ice on a roof is difficult because snow density can range from 3 pounds per cubic foot for light, fluffy snow to 21 pounds/cubic foot for wet, heavy snow. Ice density is around 57 pounds/cubic foot. One way to estimate snow load on a roof is to go to an area on the ground nearby the shed or barn. Collect and weigh 1 cubic foot of snow (1 foot high by 1 foot wide by 1 foot long). Then estimate or measure snow depth on the roof.

If your cubic foot of snow weighs 11 pounds and you have two feet of snow on the roof, then you have about 22 pounds/sq. foot of snow load on your roof. This method is based on the idea that the snow on the roof is similar to the snow on the ground and that the snow is evenly distributed on the roof. Use caution to avoid falls if you attempt to climb on a roof by using a fall arrest harness and the buddy system.

Do you know the snow load capacity of your barn or shed? Snow load capacity is determined by the truss capabilities. Building manufacturers should supply truss certificates as they erect the building.

UniversityofMinnesota EXTENSION SWINE&U

Shelterbelts

Extension agricultural engineer Kevin Janni suggests the installation of snow fences and or tree shelterbelts upwind of farmsteads SWINE & U and agricultural buildings as additional ways to prevent

By Diane DeWitte excess snow buildup on building roofs.

Proper snow fence design and location is important for protecting a building or farmstead. Some building roofs have failed in the past because the buildings were located too close to shelterbelts or windbreaks, which resulted in large snow drifts on top of these buildings.

Remember when placing a 50 percent solid snow fence or tree windbreak that snow will be deposited downwind a distance of up to 10 times the shelter belt or snow fence height. An 85 percent solid fence deposits the snow within a distance of about four times the fence height. Porous snow fences distribute the snow more evenly and give better protection downwind than a solid fence.

Leaving an area 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. If too far from the windbreak, it will be outside of the wind “protection” zone.

Moving snow around the farmstead

After a winter of heavy snow and ice, livestock owners should consider where the snowmelt will go and how it could make farm operations difficult in the spring. Kevin Janni emphasizes that early snowmelt and spring rains can run across frozen ground, gather in low spots and create flooded areas. Melting snow can flood buildings, feed and bedding storage areas in low areas, which can damage feeds, bedding or equipment. Feedlot runoff needs to be managed properly to prevent contaminating surface waters. It is also important to prevent snowmelt from entering in-ground manure storage pits or basins.

When moving snow, producers must plan for spring thaw.

See SWINE & U, pg. 19

Extension internships available

ST. CLOUD, Minn. — Each summer, University of Minnesota Extension welcomes undergraduate students interested in crops, livestock, horticulture, natural resources or communicating science to gain experience through internships. In this paid internship program, interns work closely with Extension educators to learn how Extension translates sciencebased knowledge for use across Minnesota.

The internships are held each summer for 10 to 12 weeks. Applications are now open for Summer 2022. Internships are full time, but there is flexibility based on interns’ school schedules. There are several locations throughout Minnesota.

To apply for one of the summer internship opportunities available through Extension, undergraduate students must complete the online application. If you have questions about the internship, please contact your local Extension educator.

This article was submitted by Katie Drewitz, University of Minnesota Extension. v