Barns have come a long way over the years; for one thing, they’ve gotten bigger. That’s one reason most farmers hire either hourly labor or a contract firm to build their barns. “At one time farmers did everything,” George Grandle, recently retired professor at the University of Tennessee-Knoxville’s Department of Biosystems Engineering and Soil Science, said. “In this day and age farmers have plenty to keep them busy, so finding time to actually build a barn is kind of difficult. And the expertise, too; as structures have gotten larger, some farmers just don’t have that skill set if they didn’t grow up in an area that built their own structures.”
For those who are planning to erect their own barns, Grandle said it’s important to consider the use before construction begins. For instance, many dairy barns need to have a feedway with 4’ x 8’ freestalls on either side. “You have to space out where the posts supporting the structure end up between the stalls, and not in the middle of an aisleway,” he said. “If it’s a poultry structure, generally those plans are dictated by the integrator that the farmer’s growing for; most of them are clear span structures 40’-50’ wide, using trusses to support the roof over that distance.” Even if the farmer builds his own barn, he usually will use commercially manufactured trusses; buildings have fewer posts than they used to, so the trusses are crucial for support.
Siting
There are a number of factors to keep in mind when siting the new barn; drainage is one of them. “It’s like the old saying, ‘Location, location, location’ – you want to locate in a well-drained area,” said Grandle. But if the site is otherwise situated above the water table, drainage can be improved by creating diversions for the water, particularly if there’s an upslope draining water toward the barn.
“Every site’s going to have some points of compromise,” according to Karl Vandevender, a University of Arkansas extension specialist and professor of Biological and Agricultural Engineering. “What you’re really trying to do is balance out a lot of different features and factors with the construction process, and where you site the barns.”
An example is access to utilities; ideally, you’d like power and water supplies to be as close to the barn as possible, to reduce the cost of routing them. But, said Vandevender, “If you minimize the distance to your water and electricity, that means you’re probably on the edge of the property line right there on the road.” As a result, other people might find the barn unsightly, creating unnecessary friction with neighbors.
Vandevender said farm and ranch owners need to take into account the impact of a new barn on those around them; often, he said, the first thing they’ll do when siting a new barn is to cut down all of the trees. “That removes your visual barrier that helps blend your farm into the landscape around it,” he said. “A lot of our agricultural opportunities out there are along the lines of, ‘Out of sight, out of mind.’” He said producers should build behind trees or other buildings to screen barns from passersby and reduce the likelihood of an adverse reaction; similarly, if a facility is going to have fan or tunnel ventilation, the discharge should be directed so as not to douse the neighbors with dust and odors.
Ventilation
Another consideration is ventilation. George Grandle said locating the barn on higher ground can help to dry stored hay, and is very important to the well being of livestock being housed there. Grandle suggested the inlet for air be lower and the outlet higher in the structure. “Then you can achieve natural ventilation, or the ‘chimney effect’,” he said, “where the air is drawn into the barn and seated by the animals or crop that’s housed there, and then the hot air rises; the principle takes over and it goes up and out the higher part of the barn.”
He also said, subject to local wind conditions, it’s preferable to orient barns in an east-west direction, especially if they’re being used to house animals; that way, the ends bear the full brunt of the sun when it’s lowest in the sky. “But then in the wintertime, when the sun is a little lower in the sky, you can take advantage of that southern exposure on the long side,” Grandle said. He added the barn shouldn’t be too close to trees, recommending a distance equivalent to 2-5 times the height of the barn.
Building Material
The choice of building materials is another factor. “A lot of people think oak is the strongest, and it is a hardwood that’s readily available,” Grandle said. “It’s a good framing material. But Southern pine is really hard to beat for interior framing.” Wood that’s in contact with the ground should be pressure-treated, but not any built-in animal feeders themselves, to ensure the chemicals used don’t taint the feed.
A good barn can last many years. Grandle grew up in Virginia’s Shenandoah Valley and described the “bank barns” there, structures built into the bank of a hill with stables on the lower level and grain storage up above. “A lot of those barns are over 150 years old,” he said. “The typical pole barns that we build nowadays should last 30-50 years with just normal maintenance.”
