The British obsession with the shed at the bottom of the garden reaches feverish summer madness during National Shed Week. The highlight of this week’s shedfest is the highly competitive and seriously eccentric Shed of the Year competition. Thousands of “sheddies” voted in the preliminary rounds for the best sheds in each category, from Pub Shed to Tardis, Office, Disco Shed, Eco Shed, Love Shack and Normal Shed.

This year the overall winner is the Kite Cabin in west Wales, owned by Steven Harwood. His handsome cabin stands on stilts in his wooded garden, a treehouse for grown-ups, with two bunk beds, a sofa, a TV and panoramic views of the valley beyond. A professional cabinet-maker, Harwood built the shed on a 5m wide platform in a few months, whenever he could afford to buy some more wood.

Harwood and his wife Victoria, a teacher, and their children Ella, 11 months, and Joseph, 3, live in Drefelin, Carmarthenshire, in a full-to-bursting two-bedroom cottage: “It was very impractical to put up friends and family, so this was the cheapest option. I also thought the cabin would be a great place to get away from everything to compose music and paint.”

Harwood says that the materials for the cabin cost £1,500, but reckons it would cost £10,000 to have it built. “I dreamt it up in my head, not on paper. But it works.”

Sheds are all about dreams, and leading a secret double life at the other end of the garden path. The website that runs Shed of the Year, www.readersheds.co.uk, has thousands of pictures of huts and thrillingly geeky discussions about the best cladding and nails. The competition was judged by Sarah Beeny, the television presenter, the DJ Chris Evans and Trevor Baylis, the inventor, all shed addicts.

Carol Fulton and her boyfriend Paul Crudge won the Normal category with their minimalist Applecrate shed. Fulton explains how the shed addiction begins: “You live your life blissfully unaware of sheds. Then you decide you want one for your garden. You start looking into them and despite yourself you become rather interested, and then rather obsessed. You end up wanting your shed to be the most beautifully-made one .”

The definition of the word shed is much debated — readersheds.co.uk favours diversity, but many sheddies are more traditional. The Disco Shed, owned by Patrick Bickerton, tours summer music festivals with its mixing decks, amplifiers and tacky coloured lights, all on a hut on wheels. Judge Chris Evans says: “The Disco Shed so nearly got my vote for obvious reasons. But let’s face it, it’s not a shed, it is, in fact, a vehicle.” Bickerton, at 30 one of the youngest sheddies, says: “People love the Disco Shed. Blokes can’t believe it’s a shed and want to look inside, and women like all the cheesy lights and old games.” The shed comes with a musical twister game, boules and Swingball.

Many of the sheds are for work rather than play, and the winner of the Office Shed category is Grumpy’s Palace in Jersey, where Deborah Carr writes her (as yet unpublished) romantic novels. “Sheds are so underrated, and so fantastic when you don’t have your own space in the house.”

One of the most popular categories is the Pub Shed, won this year by Andy Butler, of Haverfordwest, Pembrokeshire. His shed is a shrine to Elvis, Exeter City football club, and memorabilia from military tours. Butler, 48, has four bar stools in his Cowshed pub, “but we can squeeze in 30 people if we use the deck and garden”. This week he held a “debriefing” party for a soldier friend just back from Afghanistan. “And my wife’s really pleased to get all the memorabilia out of the house.”

The Hut category winner looks most unpromising: a wreck held together with tarpaulin and rope. But it is Hut 6 at Bletchley Park, where the British broke Germany’s Enigma code and changed the course of the Second World War.

Simon Greenish, the director of the Bletchley Park Trust, could not be more enthusiastic about his dilapidated 40ft wreck: “Here mathematicians broke the codes in messages from the Luftwaffe and the German Army,” he says.

“But now the floor is rotten, it’s sinking, and the roof has failed in places.”

Greenish is trying to raise £600,000 from the Heritage Lottery Fund and other sources to restore the humble Hut 6 and turn the interior into a modern museum for the Enigma code. It’s a big bill for a shed but, as Greenish notes: “Hut 6 is perhaps the most important wooden structure in the world.”

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