What is an oast house?

A question we get asked from time to time is, what actually is an oast house?

For us, there couldn’t be a better symbol of Kent than an oast house. Their striking shape dots the countryside skyline, providing some Instagram worthy shots – but what exactly are they?

In a nutshell, an oast house or hop kiln is a building created to drying hops as part of the brewing process.

Oast houses or hop kilns have played a huge part in the agricultural history of both the county and the country. And, at the heart of their fascinating origins is one of the nation’s favourite tipples – beer!

Starting from the top, what are hops? Hops are the flowering clusters of a plant called Humulus Lupulus and they give beer its distinctive flavour and aroma. Like grapes in wine, hops come in different varieties, each with its own characteristic. For centuries, the garden of England produced hops on an industrial scale, bringing life and prosperity to the countryside – and building on mass the oast houses seen all over Kent.

Side note: If you want to know a bit more about Kent’s oast houses, please have a read at our previous blog post.

Ok, but what do hops have to do with oast houses?

After enjoying a long summer basking in the English sunshine (in theory), hops are harvested around September. But, before they can be popped into any brews, they need to be dried. That is where the oast houses come in.

When hops are picked, they have a moisture content of 80% – which is no good for brewing. However, after an oast house has worked its magic, the amount of moisture in them goes down to a tiny 6%.

oast house history

How did a traditional oast house work?

Sitting on the ground floor of the roundel was a furnace, halfway up the tower was a slatted ceiling covered by a horsehair cloth, then above that a cone-shaped roof, and at the very top a cowl.

First, the hops were placed across the slatted ceiling. The furnace was then lit, and as the heat rose through the slatted ceiling, moisture was removed from the plants. The excess steam rose through the conical roof and out through the cowl. Not only did the cowl act as a very effective vent it was also rotated by a wind vane, ensuring that air was always circulating throughout the roundel and that the hot air had a clear path out of the oast.

Henden Manor Oast Cowl image

After the hops were deemed to be dry, they were shovelled out and placed onto the barn floor to cool. Once ready to be packed, they were pressed into large jute bags and sent to market. Just like today, brewers would not just throw any old hop into their beer so, by law, each batch was labelled with the grower’s details. This ensured that the much-loved Kentish beer would never be compromised.

As the hop growing industry in Kent declined and imported hops fell into favour, the use of oast houses declined too. Now, many of these wonderfully clever contraptions have a new lease of life as beloved homes!

Dude & Arnette are the UK’s market leader for oast cowl manufacturing, restoration and repairs. We have been the go-to family business for oast house owners since 1937.

Sue & Les Hart - Cowl

Filming an oast cowl construction with Channel 4

The guys from Channel 4 love a good oast cowl construction. Back in 2017 they featured us in their Village of the Year programme showcasing the history of oast cowls and Kent peg tiles. This time, they approached us to film the construction of an oast house a from start to finish. This is part of a programme that will showcase the build of different traditional buildings, each one being different and unique (a church, a windmill). With faces most definitely made for television, who were we to deny the public this experience?

They were particularly interested in watching us build the two oast house roundels (the roof) and the two oast cowls. As highly trained craftsmen and a fourth-generation family business, we know this process very well. We restore and rebuild oast houses and oast cowls from scratch and over the years, we have worked on all types of oast houses across the country, including buildings listed with local heritage departments.

Building an oast owl from scratch

We started the construction by pitching the two oast roofs known as roundels. We then used Tyvek (flash spun high-density polyethene fibres) to weather each kiln. After that, we used counter batten up each rafter, so that when we lathed the kiln it could hold the tile nails away from the Tyvek preventing holes. We then made onto the counter baton to work out where every row of tiles had to go so that they were evenly spread up the kiln and weathering one another.

oast cowl construction  Oast cowl structure being put together  oast construction filming

Going onto the makes we added the lath, which is wood that’s run out really thin and therefore gives us an opportunity to bend it and pin it around the roof. The lath also serves as a base for the tiles. We used tapered and square tiles as due to their shape they’re able to go around the roof without running downhill. Once the tiles were on with lead and fibreglass, the top was ready for the oast cowl.

Preparing tiles for oast construction  oast construction tiles . oast cowls built in the warehouse

The last step of the process is to add the oast cowl on top, which we are in the process of putting on so watch this space for the final snaps!

Whether you’re interested in oast construction, installation or kiln roof maintenance, get in touch with our specialist oast cowl build team for a clear, honest and concise quote and we will organise a visit to your oast house at a time that suits you.

Want to see how we finish this project? Follow us on Instagram, Facebook or Twitter for the latest oast updates.

Kent’s Oast history

Designed for the drying of hops, an oast (or oast house) is an essential part of Kent history. Kent was famed for its hop-growing, and the demand for somewhere safe to dry (kiln) the hops for the thirsty brewers was high.

How did an oast house work?

Green hops were picked in the hop gardens (for a set price per bushel), however when freshly picked they had a moisture content of 80% – this needed to be reduced all the way down to 6% to be any use for the all-important brewing.

Traditional Kent oast houses were two or three storeys high with diagonally slatted floors (stowage). Hops were strewn out across these thin drying floors and heated from below – the slats allowed the heat to gently rise through them decreasing the moisture content.

Topped by anywhere between one and eight circular kilns, the oast cowls that we so lovingly construct and restore provided ventilation for the hot air from the wood or charcoal fires below to escape. They were cleverly designed to swing away from the prevailing wind and therefore create a vacuum that kept hot air being drawn through the slatted floors above.

The hops were then left to cool before being bagged up into large jute sacks called ‘pockets’ with a hop press. Each pocket contained about 150 bushels of green hops! Most importantly, the pocket had to be marked with the grower’s details. The brewers at the market would want to know for certain, where their hops were coming from, as they were used in their breweries to add distinct flavour and character to the Kent beers we know and love.

A history respected

Starting our business in 1937 it’s no wonder we know these oast and oast cowls inside out. We are really proud of our part in maintaining this important part of Kent life. If you want to see a traditional oast house in Kent, one of the best preserved is The Hop Farm Country Park at Beltring. Famous for having the world’s largest collection of Victorian Oast Houses it has been our honour to work on this project.

If you have any questions about oast houses in Kent then get in touch.