Rickhouses are primarily made of wood, brick, stone or metal and constructed to be about seven stories high. In the U.S., a warehouse used for storing barrels of aging whiskey. Barrels are stored on ricks, stacked several high. The materials that the building is constructed from, as well as the location of the barrel in the building, can affect the maturation process.
As long as bourbon is barreled correctly, aging really has no requirement for how long or less. It can go for any amount of time. But, there are two exceptions to this – straight bourbon whiskey has to be aged for a minimum of two years, and bottled-in-bond must be aged for at least four years.