Dunnage House, Rackhouse or Steel Building Rickhouse

Rackhouses, rickhouses, dunnage houses—there are several names for buildings where spirits are aged. You may think that these terms can be used interchangeably. However, they are actually slightly different structures.

Here are the subtle differences between the features of rackhouses/rickhouses and dunnage houses.

Dunnage House

Dunnage houses are traditional, short, slate-roofed warehouses. They typically have earthen floors and thick, stone walls. Each floor of a dunnage house can hold the height of around three stacked spirit casks. A dunnage house might look a lot like a wine cellar from the inside.

Today, the number of distilleries exclusively using dunnage houses has dipped. The major reason for this is that dunnage houses are comparatively less efficient in terms of space and storage capacity than the alternative options.

Temperature Stability

Dunnage houses are often operated by scotch whiskey distilleries. The temperature fluctuations in such places are fairly minimal as they are great at absorbing and regulating heat.

The temperature swings in dunnage houses are less extreme as compared to other types of aging facilities. The single storey structure, vs a multi-storey structure also helps maintain temperature stability.

This leads to lower evaporation losses, or angel’s share, and a more consistent maturation process throughout the entire dunnage house.

Rickhouse/ Rackhouses

These terms are interchangeable. Rickhouses, or whiskey aging warehouses, are the modern equivalent of whiskey storage warehouses containing large racks.

In most whiskey storage cases, casks are palletized. This is done in an upright position so that the warehouse workers have an easier time moving the barrels with equipment. The alternative method would be to store the barrels in structures called ricks or racks. In the ricks, they store the barrels on their sides. 

A wide range of sturdy materials are used to construct rickhouses. Some of these include wood, brick, stone, concrete, tin, and metal.

Evaporation Rate

No matter which material your rackhouse is made out of, it’s probably going to experience seriously hot temperatures. This is especially true in the summer months.

The excessive heat means that the aging process will likely speed up slightly. Unfortunately, it also means a relatively faster evaporation rate and consequently, greater evaporative losses, or angel’s share.

There are often several storeys to traditional rickhouses. From three, five, to even seven storeys, and you’ll see that the aging process differs on each level.

You can skillfully blend the barrels, successfully achieving product uniformity. On the other hand, the variation in aging also opens the door for single-barrels to create some truly interesting flavor profiles.

Spirit Maturation—Dunnage Houses vs. Rackhouses

Many distilleries take advantage of the fact that the whiskey matures differently depending on the type of warehouse used and the external conditions. This creates a wide range of spirits varying in concentration and taste.

These spirits can easily be blended together to create a unique house style. Sample 3 different barrels of approximately the same age, one from a dunnage house and the other from a rickhouse to really understand the difference.

Suppose the dunnage barrel was placed near the ocean, in a high humidity environment, while the other was placed in a dry place. You’ll notice a huge difference between the two.

The dunnage barrel may also have become more influenced by the environment it was placed in. This’ll give it is a more briny characteristic.

What You Need To Know About Barrel Location And Maturation

Different distilleries have their own preference of the type of rackhouse they use for spirit storage and maturation. There can be a wide variety of materials chosen for the construction of these warehouses. Some include brick, wood, tin concrete, and so on.

It’s not just the storage structure that affects the maturation, the location of the barrel itself will also have an effect. Where each barrel is placed has a great impact on the aging and maturation process of the spirit.

When rotating barrels, there are several methods to move barrels around. You can use escalators or even forklifts. 

The most common rackhouse type is the traditional elevator type. A traditional elevator rackhouse has 9 floors and can roughly hold around 20,000 barrels—approx. 1 million gallons of bourbon.

Location: Top of Rackhouse; Maturation Rate: Fast

The seventh to ninth floors of a traditional rackhouse are considered to be top-of-a-rackhouse barrel locations. The atmosphere in this area is typically hot and dry.

As a result, water molecules—which are a lot smaller in size than alcohol molecules—escape from barrels. This effectively drives the proof at the very top up to nearly 145!

Location: Bottom of Rackhouse; Maturation Rate: Slow

The first to third floors of a rackhouse are considered to be the bottom locations for barrel storage. The atmosphere of this area is relatively cool and moist.

As a result, the small-sized water molecules from the surrounding air moisture easily penetrate into the barrel. This effectively drives down the proof level of the barrel to around 110.

Location: Middle of Rackhouse; Maturation Rate: Average

The barrels situated at the middle of the rackhouse are termed ‘center cut’. The spirit maturation rate stays constant in these barrels and experiences only the slightest fluctuations compared to those placed in extreme locations.

1 High, 2 High, 3 High Barrel Locations

In a traditional 9-floor rackhouse, there is the capacity to store 27 barrels if there are a total of 3 barrels on each floor. These three barrels are called 1 high, 2 high, and 3 high. The barrel proof level varies from floor to floor.

The barrels situated on the inside of the rackhouse have a different aging process compared to those placed on the outside of the rackhouse.  This is because the barrels located on the outside are closer to the rackhouse walls and thus, receive more heat.

Effect of Evaporation on Flavor

The concentration of the flavors inside a barrel can be affected by the rate of evaporation. This is because the barrels placed on the top of the rackhouse experience an accelerated evaporation rate. As a result, there is greater concentration of spirit, which in turn impacts its flavor.

On the other hand, since barrels placed on the bottom of a rackhouse experience a slower rate of evaporation, the water molecules entering the barrel make the spirit more dilute.

The spirits with bold flavors and a particular in-mouth feel are usually placed at the mid high and high storage locations. These barrels can also be mixed together to give a more consistent taste.

About Allied Buildings

From building rackhouses, distilleries, wineries, and breweries to constructing distribution centers, aging warehouses, and tasting facilities, Allied Buildings has successfully completed 4500 buildings in 65 countries.

We have a talented team of experienced spirit industry experts to serve you.

Whether you’re building large production houses for master brewers or tasting rooms, aging houses for premium quality spirits or full capacity aging warehouses. We guarantee fine quality and timely construction for all structures.

Check out some of the projects we’ve completed.