When laying out a horse stall design for your horse stable, it is wise to plan ahead. Sometimes there will be a need for a larger stall than normal. The 12′ width of a stall is fine for needs, but when foaling season comes, stallions are being stabled, or a horse gets injured, sometimes a larger area is needed. Many times referred to as a “foaling stall”, this larger area can be achieved a few different ways. A smart way is to simply add six feet to a stall, resulting in a 12′x18′ area. To achieve this a slip board construction can be used between stalls. The boards are simply slid into a channel on the opposite wall. Many times made from 2×4’s, the vertical channels hold the boards, then they are each screwed to the wall. This flat construction of the channel is not harmful for the horses and as each stall is built, a channel can be installed every six feet. Then the boards can be moved as needed. This is ideal for a foaling situation. The mare and foal pair need the extra room, but once Jr. is weaned, the stall wall can be moved back to the 12′x12′ setting. Then each horse can have their own area.
For stallions, the additonal six feet design to a stall gives them more freedom of movement. Saddly, stallions are many times stabled the vast amout of time. Fencing and paddock issues force the confinment. But giving the big boys some more room can also help to relieve some stress, help with circulation, and also give the handlers more room to work around them.
Foaling stalls can also be used when weaning the foals. If two foals are being weaned at the same time, the foaling stall is a great place to keep them. The extra room allows for the two to be stabled together. This also helps the babies form a new friendship while they are breaking away from mom.
Sometimes a barn gets crowded. In almost every stable there is a small pony. If the stalls are arranged with the six foot option, it can be useful to place a small pony in. A Shetland has no problem with a 6′x12′ stall. But care should be paid that a larger horse does not get into that particular stall. If a large horse has to be put into it, be sure they are tied and then backed out. Turning around in that narrow of an area result in a horse getting stuck.
Foaling horse stalls are a great use of space and by utilizing the slip board idea, the horse stable owner has more flexibility. Meeting the needs of these gentle giants is a pleasure to those who really love them. 
[...] Another area of design is the stalls themselves. We have already established the need for 12′ in width. The next area is the length of the stalls. 12′x12′ feet is very good. For foaling or stallion needs the 12′x18′ is many professionals choice. For more ideas on this read my post horse stall partitions. [...]