The architect of one of Grand Design's most dramatic homes has recalled the moment a workmen fell through the roof.

Richard Hawkes, from Staplehurst, has described the moment his unique roof design collapsed before his eyes, while filming took place for the Channel 4 show.

As presenter Kevin McCloud spoke to the camera, a loud noise could be heard and the roof was seen crumbling behind him as a contractor fell through the eco-friendly arch he had created for this new home.

The unique design, the world’s largest timbrel vaulted arch, was completely unsupported comprising of a 100mm thick layer of tiles and Plaster of Paris which had only previously been used to build domes.

Builders had been told not to lean on the structure during construction as it is only the completed combination of layers which gives the structure its strength.

But a stonemason leaned on the first layer of tiles and fell through the roof.

Fortunately, a crash mat below saved him from injury and he escaped with just a graze to his head. The falling material was also undamaged.

But the accident set the project back one week.

He told The Sun: "One of the things they were told not to do was lean on the first layer of tiles. It's extremely delicate.

"It's the subsequent layers that make it stronger. He leaned too much. It made part of it fail and whatever that was left fell with it. So that was dramatic."

Mr Hawkes, 49, came up with the unique idea after falling in love with the plot of land, which housed a tiny cottage.

He wanted to create an eco-friendly home that would blend with its surroundings and use local materials.

Mr Hawkes used structural engineers from the University of Cambridge to help him create the design and tested a model version first.

He added: “Kevin and I built a little mock-up and Kevin was convinced it would break.

"We stood on the little arch. It set the jeopardy up. We stood on it and it held us both. Then we stepped off. It was one layer thick.

"It was cleverly thought through and was a fantastic technique."