Pioneering ‘hobbit house’ couple Heidi and Sav Pavlou are racing against time to install their roof before the weather turns.

The couple's “green” house will be built of recycled tyres filled with earth and will be totally self-sufficient. It will be covered with a layer of earth to keep it insulated.

Sav admitted: “We are behind schedule. We were expecting to have the roof on by now. This week we were hoping to have the electrics in but the house is still open to the elements.

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“We have four or five weeks before the weather changes and this site becomes a quagmire.

“It is urgent we get the roof on as soon as possible.”

Some of the delays have been caused by red tape as the couple ensure the groundhouse – the first in Britain to be authorised for domestic use – meets all specifications.

But a shortage of carpenters has also led to work stalling.

Video: Work is shaping up on the unique 'Hobbit house' build

Mum-of-five Heidi said: “We have had a wonderful team of fantastic, crazy characters from around the world helping us during the summer, but the project now desperately needs specialist carpenters to erect the wooden trusses so we can get the hat of the house on.

“Once that happens we are hoping to be ‘glamping’ inside for Christmas.”

At the moment, much of her family is sleeping at her parents’ house.

The roof will eventually be covered with grass so it blends into the countryside flanking Elmley Road in Brambledown.

The couple have sunk £180,000 of their own money into the extraordinary project after selling their home in Newington.

They are building on land once owned by Heidi’s grandparents.

The walls are made from 800 recycled car tyres filled with chalk and covered with a layer of London clay inside.

Outside, they are being clad in Kentish ragstone and flint.

The front of the south-facing five-bedroom single-storey house will be mainly glass.

Volunteers from around the globe including Italy, India, Australia and America have been working on the scheme.

Currently on site is Alejandro Gorgon from Argentina who joined two months ago.

Film actor Peter Forrest, who performs as a talking dog in London’s Covent Garden, has just left to appear in a new film with Hollywood star Ben Affleck.

Still on board are Heidi’s carpenter cousin David Urmston from Whitstable, Islander Kai Burton, who designs film props, and ex-builder Rod Tranah.

A bank of solar panels to create free electricity has been installed by M3 Solutions.

The latest recruits to join the gang are Mrs Green, Barbara Bob, Nugget and Trevor – four ‘rescue’ chickens.

Heidi said: “They are like dogs and follow us all over the site.”

She added: “We’d like to thank everyone who has helped us come this far, including the staff at Standford Hill Open Prison’s recycling department.”

n If you are a carpenter and think you can help, email Heidi at groundhousesheppey@yahoo.co.uk. For progress reports see the couple’s Facebook page Groundhouse Sheppey.