Any novel with horses in it, unless it’s about wild horses, sooner or later will end up in a barn. It might be a cave or a fallen tree or a hollow in a hillside, but at some point, your characters are going to want to get their horses in out of the weather.
Barn design is heavily dependent on climate, construction materials, and local tradition, but since all horses fit into the same pattern of behavior and size range, some things are standard. For a normal-sized, non-miniature horse, a stall smaller than 10 feet square is pushing the limits of equine size and comfort. The exception would be what we call “standing stalls,” which can be no longer or wider than the horses tied in them. But these are much less comfortable than box stalls or “loose boxes,” where horses are free to turn around and even stretch out when lying down.
The best a horse can do in a standing stall is tuck up his feet and lie down for the short periods each day when he needs to get off his feet. This sort of stall is most common in urban stables and for horses who spend most of their day working; when they’re stalled, they’re eating or waiting to be taken out to work again. Livery horses, coach and cab horses, and riding-academy horses might take their rest breaks in standing stalls. Horses in box stalls are more likely to be worked only an hour or two a day, as would be the case with privately owned horses in boarding barns.
What kind of structure the horse is trying to lie down in depends on where the horse lives and what materials are most easily available in the area. In parts of Europe, that would be stone. In the northern US, wooden barns are common; in the desert Southwest, steel-frame structures are pretty much the standard.
A cold climate needs a barn that keeps the animals warm inside, allows ample storage for large amounts of fodder through the winter, and still allows ventilation. The high peaked roof of a New England barn allows snow to slide off, and also has plenty of room in the top for the hayloft. The stalls will be smallish (10-12 feet at most, as a rule), with small barred windows to the outside, which can be shuttered or closed against the weather, and a large, high door at one end at minimum. The barn may also have an indoor arena attached, for riding in inclement weather–size is determined by the budget and the available space but will usually be at least 50 by 100 feet, and often larger. Stalls will tend to run in two rows separated by an aisle 12 feet or more wide–wide enough for horses or humans to walk down the middle without being snagged by horses with open stall doors, and for horses in facing stalls not to be able to reach out and touch one another.
The floor of a barn may be concrete in the aisles, covered with rubber matting or some form of tiling that is highly impact-resistant and non-slippery. (Horses’ hooves, and especially shod hooves, do not play well with low-friction surfaces, which would include concrete and asphalt.) More likely in an older barn it will be hardwood, or packed dirt. In the stalls, concrete is not the best idea as it’s very hard on horses’ legs and feet. If the floor is a solid substance (often with some form of drain), it will be covered with rubber matting. More likely in many barns, the rubber mats will be laid down over packed dirt, and then the horses will be bedded with something soft over that: straw in the old days, wood shavings more recently (but be careful of the source: black walnut is highly toxic to horses; most barns use pine shavings, and sometimes cedar).
In milder or hotter climates, the barn design will change. Ventilation and coolness will become more important than warmth. Hay storage will shift to a separate or attached building, because hay packed closely together at high temperatures will combust–and keeping it ventilated is crucial. The barn will be mostly open, with larger windows and doors and lots of cross-ventilation. Stalls may run in single rows around a courtyard (a style popular in European stables, too), or will open into paddocks or corrals. The most basic and airy form is the shade pen: a steel half-roof above an open pipe corral.
It doesn’t matter how fancy the barn is. Marble mangers and crystal chandeliers are impressive, but horses and their feed are dusty and messy and need a lot of cleaning up after. Real horsemen may have a fancy facade out front, but the places there the horses actually live will be plain, functional, and above all safe.
Horses will accommodate themselves to just about anything you put them in, but they are by nature and design free-running steppe animals. Keeping a horse in a box causes everything from respiratory problems to obsessive-compulsive behavior, and a young horse will fail to develop properly. He needs exercise, and lots of it.
Barns, therefore, nearly always have some form of turnout available for the horses. Thoes that do not will expect the horses to be ridden or worked for at least an hour or two daily. Those that do may only have a handful of small corrals, not much more than two or three times the size of a stall, for horses to take turns in, an hour at a time; or the indoor or outdoor riding arenas may double as turnouts. In an ideal situation of course, the farm has acres of beautifully fenced pasture, or at least a decent half-acre or one-acre paddock, in which the horses are turned out all day or all night, or for several hours at a time. Some of these pastures in fact may be permanent living spaces for horses, with shades or shelters to protect them from the weather.
Fencing is a very important aspect of horse stowage. Vital, in fact. Keeping the horses in and separated from each other as required by their gender, personalities, and individual needs requires good fencing and plenty of it.
Because horses are relatively thin-skinned and often inclined to find ways to injure that skin in catastrophic ways, the absolute worst fencing for a horse is barbed wire. Want to rip your horse to shreds? That’s your fencing. High-tensile wire is not the best idea, either, unless you like the effect of a tomato slicer on your horse’s leg.
Ideal fencing is board fencing, well and often maintained and set off with electric wire to keep the horses from chewing on it. Wire mesh fencing works, if the mesh is small enough–2×4 inches is safe and effective. So does electric fencing (wire or tape), though some horses will walk right through it. Stone walls and timber fences have an ancient and honorable pedigree–as long as they’re high enough (no less than four feet, preferably five or higher) to keep the horses from stepping or jumping over them.
And there you have it. Shelter, containment, and safety for your horse. We’ll assume the availability of water and feed, too, but that’s another post.