Phil and Charlotte Newby bought a walled garden near Barnsdale five years ago. They left their four bedroom home in Queen Street, Stamford, after getting permission to build one of only 33 earth sheltered homes in the country.
The single storey four bedroom home will have a grass roof, a glass front and collect its own rainwater. It will supply some of its own electricity and have almost zero utility bills.
Despite relentless rainfall this summer, 300 cubic metres of earth has been dug up to make room for the house.
Phil said: "Charlie and I pictured a summer of barefoot children and barbecues and we've been mud and wellies. I hope we get an Indian summer."
Work is on budget - about £140,000 - and on time, about a quarter of the way through.
Phil hopes the home will be watertight at Christmas and finished by July next year.
In the meantime, its a tight squeeze for Phil, his wife Charlie, both 36, and their two children Jessica, two, and Sasha, who have moved into a small cottage on the site that has just three rooms in total.