Where do you store your hay? If it’s in your main barn, there are good reasons to think about putting it somewhere else. Here are two:

• Hay—even good hay—is dusty. Hay dust and particles filtering down from a loft contribute to equine (and human) respiratory problems.

• Baled hay can undergo spontaneous combustion, becoming both the fuel and the ignition source for fire.

For safety, says farm insurance agent Kathy Kane of Smith Insurance in Rhode Island, “Try to store the hay in a separate building from the animals.” Then if it goes up in smoke, your horses—and your business—won’t go with it.

Thus, putting your hay in a separate hay barn may save you money on insurance premiums, too. Any building where hay is stored carries a surcharge because of the fire risk, Kane says, but the surcharge will amount to less on a less expensive accessory structure. And whether it’s a new building or an existing structure retrofitted for this use, a hay barn can be very simple—as long as it protects the hay from the elements.

For some hay-barn basics, we gleaned advice from Cooperative Extension engineers at Virginia Tech, the University of Missouri, and Pennsylvania State University. If you’re building new, they say, remember that in many areas today, even farm buildings must meet the state and local building codes and zoning requirements (if any). Check to see what permits will be required before you break ground.

Where to Put It

Choose the site carefully—you can’t change it later. The perfect spot is:

• high and dry, not in a low spot where water collects or in the path of storm runoff.

• level.

• accessible to tractors and delivery trucks. Determine the largest truck that will need to reach the building and make sure there will be room for the truck to off-load and turn around. Semi-trailers need at least a 55-foot turning radius.

• convenient to your main barn. You’ll keep the bulk of your hay supply in this structure, and bring to the main barn only the amount that you’ll use each day.

• far enough from the main barn and other structures to minimize the risk of fire jumping from building to building. One recommendation is 75 feet, but check with your insurance agent and the local fire department for guidance.

The greater the distance, the greater the protection. You may not have a perfect site on your property, but you’ll be happiest with the end result if you can come as close as possible to the ideal. Once you’ve settled on a site, have it professionally graded to ensure that it’s level and that water will drain away from the building.

What to Build

A hay barn should keep sun and rain off the hay while permitting as much ventilation as possible. In a fairly dry region, an open-sided shed will do that; in wetter climates, a barn that’s open on one side or at the gable ends can suffice. The structure should be clear span—you won’t want to stack hay around interior supports.

Beyond that, your options are wide open. Get bids and weigh the costs, convenience features, and aesthetics of different types of buildings. Because construction costs vary widely by area, as well as by building design, we haven’t tried to estimate them here. Generally, though, post-frame barns and hoop barns are two cost-effective choices.

• A post-frame (or pole) barn is built on posts set into the ground on concrete footings or anchored to a concrete foundation. Pre-engineered post-frame buildings are sold by several manufacturers, or you (or your contractor) can build your own. The MidWest Plan Service has some simple hay barn plans at www.public.iastate.edu/~mwps_dis/mwps_web/hy_plans.html.

• Hoop barns use arched metal supports, set in the ground or on wood or concrete walls. A waterproof cover is stretched over the supports; it must be properly tensioned to withstand wind and weather. Hoop barns are more economical to construct than pole barns, but less flexible in design (access is from each end only). Makers generally warrant the structure for 15 years.

A full concrete slab isn’t necessary for either type of building. You can cover the building footprint with a fast-draining base of compacted crushed rock or gravel, installed over a layer of filter fabric to keep the material in place.

How Big?

How much hay do you want to store? One rule of thumb is to provide 250 cubic feet of storage per ton for small square bales, or 310 cubic feet per ton for large round bales (they are less dense). An area 10 by 12 by 40 feet, then, could store about 19 tons of small bales—the amount that might arrive, say, on a 48-foot flatbed truck.

The interior of the building that stores that hay would need to be a bit larger, however, because stacking hay directly against the walls or up to the roof encourages moisture to build up—leading to spoilage and mold. Add at least a foot on each side and two feet above the stacked bales for air circulation. Along an open side, provide enough roof overhang to shield the outermost bales from windblown rain and sunlight, which can cause the hay to lose nutrients.

Key Features Consider these factors in the design:

• ventilation. Design a fully enclosed building to be as open as possible in the gable ends, to help heat and moisture given off by the hay to escape. In addition, eave and ridge vents (or cupolas) will make the barn cooler and reduce corrosion of a metal roof. In a large building, consider installing a fan that will switch on automatically when the temperature inside hits a certain point.

• orientation. Face open areas away from prevailing storm winds. If storms blow out of the north, for example, the open side of a three-sided shed should face south. The gable ends of a fully enclosed structure should face east-west.

• access. Doorways must be wide and tall enough to fit the largest piece of equipment—truck, tractor, or trailer—that will need to enter. If you want to drive through the building to load or unload hay, allow for an aisle wide enough to accommodate the equipment.

• lightning protection. Like any farm building—especially one that stores a flammable material—a hay barn should have a lightning protection system that routes lightning on a controlled course from the air to the ground. (Guidelines are online at www.cdc.gov/nasd/docs/d001001-d001100/d001010/d001010.html or see the May 2007 issue of Stable Management, “When Lightning Strikes.”)

Good hay storage makes sound business sense. After all, depending on what you buy and where you buy it, you’ve paid anywhere from $100 to $200 a ton for the hay you’re feeding. You don’t want to lose any of it to dampness, spoilage, or mold.