Help with insulation for cool room

[Timber1]

Going to be building a cool room for the first time and just want to be sure to insulate it properly. It will be in the Southeast corner of our barn. The walls have 6x6 posts and metal siding on the outside. The roof is 8' on one side and 13' on the other and the area is 24x24. Using a self-contained whole house ac unit my uncle used for his house for years. Just have no idea as to how to insulate it, any help would be greatly appreciated.

 

[GoWyo]

About 3-4 inches of spray foam works well and seals tight.  Handles moisture better than the other types of insulation.

 

[Tallcool1]

The spray insulation is certainly the best option for a couple reasons.

In addition to the previous post, you don't have to cover it. You can put panels or gates 12" from your walls (so the calves can't touch it) and you're good.

The spray foam is expensive but you save in framing materials.