The popular Channel 4 show documents the architectural highs and lows of ambitious self-builders with unusual properties to convert. Hosted by Kevin McLoud and watched by two million viewers, the programme has helped families make fortunes renting out their homes.
After struggling to meet budgets and deadlines to complete their projects, the pay-off has been sweet for some owners, according to research by the Telegraph which has found that at least 10 per cent of properties featured on the show are being rented out with an 'as seen on Grand Designs' tag.
The report claims that on some rental sites, including Airbnb, the daily rate can be three times higher than most in the same area.
The Kinver rock house, a one-bedroomed converted cave, is available for rental for £245 per night which is around four times higher than the average rental for two people.
The Rockhouse Retreat, carved into an 800-year-old rock in the Wyre Forest, near Bewdley, featured on the programme in 2015.
Now dubbed 'Britain's first luxury cave house', it was described by the programme-makers as one of the most exciting properties ever to appear on Grand Designs when it was featured in 2015.
Owner Angelo Mastropietro, 41, bought the 2.5 acre derelict site for £62,000 but was initially told by planning officers he could not build a house in the cave. The plan was eventually approved after various ecological and biodiversity surveys to ensure surroundings were not affected.
More than 70 tons of rock was excavated from the cliff face to provide enough space for the project which included a king-sized bedroom with a wood-burning stove, a snug sitting room, pebbled shower room and all-mod-cons kitchen. It was also fitted with electricity, running water, underfloor heating and wi-fi.
The house, in Low Habberley, between Arley and Kidderminster, took eight months to complete.
And although he lived in it himself for a while whilst working on it, Mr Mastropietro soon put it on the rental market as a 'one-off cave-house experience' for people who want to escape from it all.
'I never intended to live in it'
The father-of-two told the Express & Star: "Grand Designs gave the impression I was going to live there myself but the plan had always been for it to be a holiday let, I never intended to live in it.
“We’ve had guests from all over the country and abroad, like Germany, Italy and Japan. We have some people who have returned and stayed again."
Other examples given were a couple from South London who converted a tiny space in Peckham into a three-bedroomed, eco-friendly home with a sliding glass roof which they rent out on Airbnb for £255 a night.
The Dome in the Lake District was called 'awe inspiring' when it was on the show in 2010 – with a swimming pool, sauna, four-poster beds and glorious views of Cumbria – and was until recently being rented out for £1,490 a week.
The four-bedroom Apprentice Store, one mile from Bath, in Somerset, was lovingly restored over five years to create an open-plan space with beautiful views overlooking green rolling hills. It is currently listed on Airbnb for £495 a night.