I would not lock the barn either, you just never know. A tack room located in the barn with a lock is a good idea. If you are worried about theft of your horses, maybe a dog to stay in the barn area? Also, do shut off the lights when you leave or at least have them on a timmer. Horses need to sleep too! One thing I do not like about sand, is that it makes the horse sooooooooo dusty and sand dust does not come off very well with a brush! I know form expierence!