Down at the bottom of the garden: Modern follies and chic treehouses are more popular than ever

Improving weather and a housing downturn have one thing in common. They both oblige people to make the most of their home – and that includes the garden. With fewer people moving house in this era of austerity, more are attempting to maximise the play, relaxation and entertainment potential of their existing homes by building treehouses, grottoes and full-blown follies in their outside space.

Mary and Christophe Lamper have just commissioned a folly to be built this spring in the garden of their three-bedroom house near Honiton in Devon.

"It's an 18th century blacksmith's home and the rear garden is overlooked. We thought a folly – it's likely to be a small castle if planners agree – will look towards the garden and give more private space and complement the eccentric nature of the home" says Christophe.

The Lampers' folly will be far smaller than the example built last summer for the Dorset millionaire William Gronow-Davis, who now enjoys a 65-foot tall tower shaped a little like a tall Japanese garden pagoda, on part of his 750-acre estate. "It's unusual and looks beautiful from my house. It's wonderful and finishes the garden off" he says.

Ringo Starr, the ex-Beatle, has one too. Called The Stumpery, this one really does fulfil the definition of a folly as a building with no specific purpose. It is a 'grotto' measuring 25 feet wide, 10 feet tall and another 10 feet deep, made from old driftwood and originally shown at the 2006 Chelsea Flower Show. It now sits in Ringo's Los Angeles estate.

There are 1,800 historic follies or grottoes dating from the 17th to the 20th centuries, according to the Folly Fellowship, a preservation group. And in recent years there's been a marked rise in the popularity of compact modern follies, according to the organisation's Mary Bright.

Most follies tend to be found in some of our most expensive homes; on the market now is Pitland Street House in Surrey with a Victorian folly but a £3.75m price tag, while the Old House at Coombe Bissett in Wiltshire has a two-storey folly just for you...if you have £2.285m that is.

But 21st century follies are usually significantly more affordable, growing in number and customised to suit today's more functional lifestyles.

Jayne Tarasun, a Cornish furniture maker and fine artist, is one of Britain's new generation of folly makers. Most of her follies are tailored to modern planning regulations and made from chestnut, cedar, oak, copper and glass.

Most of her creations have mezzanine levels where owners can sit and survey neighbouring gardens but her designs carefully allow panels and windows to be moved to ensure the folly-dweller and the folks next door to both maintain their privacy. Some come with cladding and insulation to make them usable during winter months, while external colours vary from white to purple.

"My follies seem to appeal to women more than men, who still prefer their garden sheds. But the idea is to have an area where people can escape - somewhere they can regard as completely private space whether it's space to think in, or read in, or sleep in", says Jayne, who has studied art and the history of follies at Cheltenham and Barcelona.

Most buildings emerging from Jayne's Folly-Smith business are 10 feet tall and are designed as contemporary towers, usually with under 10 cubic metres of internal space to satisfy planning rules. A standard folly costs less than £10,000 although highly customised examples have cost twice that. Jayne has plans for a lower price flatpack folly in the future and in recent months has worked on several smaller building plans.

If your garden building is aimed at children rather than the adults, then a smaller sum – usually £5,000 to £8,000 – will get you a stylish tree house from manufacturers like High Life Tree Houses, Blue Forest and Castles Carey.

These days such constructions are more than just a few planks around the old oak tree. Depending on the size of the garden and the generosity of parents, some tree houses include walking decks, rope bridges, climbing ropes, slides, swings, monkey bars and even zip wires for children (and probably adults) to whizz down to garden level.

Unsurprisingly, as treehouses and modern garden follies have proliferated, so they have come into conflict with the planners.

In October 2008 planning rules were relaxed to make it easier for owners to extend homes for additional living space. But the changes also 'tidied up' hitherto-ambiguous planning rules on outbuildings and sheds. Follies and grottoes are often built in larger gardens so provoke few controversies but planners say tree houses can be more controversial, and insist the new rules are not merely red tape.

Their worries are over size and surroundings and, to be fair, some owners clearly use the term 'tree house' to cover large structures overlooking neighbours and sorely out of place in, say, a conservation area. As a result, neighbourly disputes caused by tree houses built pre-2008 can be bloody affairs.

"Anyone in the treehouse next door can see into our garden, making entertaining and sunbathing difficult. The teenagers who use it can be very noisy and stay until late evening during the summer, which causes problems too. And that's ignoring the fact that it's an eyesore in an area that's otherwise very pretty" says one Winchester home-owner who has had a dispute with his neighbour for over two years.

Voluntary and professional mediation services – which offer to arbitrate between warring neighbours – report an increase in disputes over privacy and problems caused by garden noise and structures overlooking neighbouring properties. Even so, the mediators say these rows are dwarfed by the number of disputes over uncertain boundaries between houses and fast-growing leylandii trees.

Disputes apart, our more straitened times may provide an unexpected boost for the idea of creating something akin to an extra room in even a small outdoor space. Fewer people are moving and more are improving, including in the garden.

Now all we need is that mythical beast, a barbecue summer.

Useful contacts

Jayne Tarasun (Folly-smith.com); High Life Tree Houses (Highlifetreehouses.co.uk; 0208 347 4018); Blue Forest Tree Houses (Blueforest.com; 08455 190 599); Castles Cary (Gardenhomeoffices-treehouses.co.uk) Folly Fellowship (Follies.org.uk);