What Is a Dunnage Warehouse, and How Is It Different from a Racked Warehouse?

Published February 1, 2024 by John Fegan

A dunnage warehouse is the old-school, traditional type of whisky warehouse. The kind that appears on every distillery tour as if it were a living museum exhibit entitled “How Whisky Used to Be Stored Back Before Anyone Invented Practicality.” You may even have sipped a glass in one, feeling very authentic and slightly chilly. They are charming, atmospheric, and largely abandoned in favour of something less poetic and more sensible, because they are about as efficient as a Glasgow pub lock-in on a Monday morning.

Whisky, as any sensible person knows, does not spring fully formed from the head of a distiller like some sort of alcoholic Athena. No, it has to age, which is a polite way of saying it spends several years sitting quietly in a wooden barrel while mysterious chemical wizardry takes place in the dark. Seventy percent of its flavour appears during this waiting period, which is why whisky is not stored in plastic tubs next to last night’s leftovers.

So we end up at the warehouses. Not the bleak industrial sort where forklifts sulk and boxes go missing, but the gentler kind where whisky rests in rows of slumbering barrels. People wax poetic about them and say things like “hints of sea-kissed heather” as if they’re narrating a fantasy epic instead of describing alcohol.

Now, a normal person might think a warehouse is just a big shed where you stack things until somebody wants them. The whisky industry finds this idea charmingly simple-minded. It has categories. It has distinctions. Whisky storage is more like a religion, complete with sects, schisms, and believers who’d probably glass you if a pub debate got any more heated. Two of the rival factions are the dunnage warehouse lot and the racked warehouse brigade.

Dunnage Warehouses

A dunnage warehouse is the traditional, old-fashioned type, dating from an era when things were built properly, with stone walls, slate roofs, and no instructions written in Swedish. They are small, squat buildings only tall enough to stack three barrels high, which means the whisky gets excellent airflow and the workers develop a close personal relationship with back-pain.

The floor is earth. Not polished concrete, not industrial resin with sealant, just earth, the kind that has absorbed generations of escaped whisky vapour, and on bad days split casks. It smells faintly of angels who have been drinking on the job and trying very hard to pretend it is part of the plan.

They are labour-intensive. Machinery doesn’t fit in them, because the people who built them did not plan ahead for the invention of forklifts or indeed anything more advanced than a man, a plank, and a deep sigh. These are either deeply charming or infuriating places, depending on whether you are the one moving the barrels.

Racked Warehouses

These are the modern upstarts, the sort of warehouses that look as though someone asked the question “What if we made it bigger, louder, and slightly more dangerous?” and then got planning approval. They are tall, bright, and built out of concrete, brick, and something that looks very much like corrugated optimism pretending to be a roof. The barrels are stacked eight to twelve high, turning whisky storage into a vertical sport. Forklifts zip around like caffeinated hornets, operated by workers who have never once thought fondly about mud floors or the aching nobility of manual labour.

The walls are thinner, the roof is tin, and the inside temperature swings around with the seasons like a hormonal teenager deciding on a personality. This affects the whisky, which expands in the heat, contracts in the cold, breathes like a pensioner at the top of a hill, and is stolen by the local clan of angels. Calling this the angel’s share makes it sound whimsical, which is far better than calling it evaporation and a tax complication.

Temperature, Humidity, and the March of Time

Temperature and humidity now take the stage. Heat pushes the whisky deeper into the wood to extract flavour, while cold pulls it sulkily away again. Humidity decides how much of the whisky escapes, either slowly and politely in a damp place or rapidly and expensively in a dry one. Dunnage warehouses, those old stone dwellings that smell faintly of ancient mud and older whisky, tend to be more humid. This slows the ageing process and pleases the sort of person who thinks whisky should mature at a pace somewhere between glacial and geological.

Which Is Better?

And so we reach the grand philosophical debate, the sort of question that causes whisky experts to stroke their beards, stare into the middle distance, and then argue for several hours over something that cannot be measured without clipboards and charts. Is it nobler to honour tradition, with slow ageing and stone walls, or to embrace the towering racks of efficiency? Does whisky taste more meaningful if it has been rolled into position by a man who communicates exclusively in Gaelic expletives, rather than lifted by a forklift called Dave, who only communicates in reverse beeping?

Science shrugs, checks its notes, and says: No definitive answer.

Most distilleries, being sensible in the way that only extremely cautious people dealing with billions of pounds worth of alcohol can be, now use both kinds of warehouses. This is the whisky industry’s way of saying, “We believe in balance, and also in not putting all our barrels in one architectural style.” However, the vote seems to be in. Less than four percent of Scottish whisky now slumbers in dunnage warehouses, which means tradition is not dead, only outnumbered and probably muttering in the corner about how things were better when floors were made of dirt.