Grand Designs follows the journeys of some of the UK's most ambitious self-building projects, right from the blueprints up until the moment the participants are brewing up in their new home.
He revealed that a man who was starring on the show had passed away during the making of the home renovation programme.
The 64-year-old, who has presented the Channel 4 series since its debut back in 1999, told of his sadness at the tragedy that struck during the filming process.
"We are doing a very difficult project right now," McCloud told the New Zealand publication Stuff.
"We had no idea and neither did our contributors, but the husband fell gravely ill and has passed away during the filming process, and it makes the narrative very hard to graft.
"Because you think, where do we go [from here]?"
He didn't go into further detail regarding the heartbreak that has rocked Grand Designs, but he went on to pay tribute to another participant who passed away during filming also.
McCloud spoke fondly of Nat McBride, who was in the process of building his dream family home when he appeared in an episode which aired in 2010.
But his plans were left hanging in the balance as he revealed he had been diagnosed with stomach cancer on-screen.
Nat sadly passed away six months later.
However, his grief-stricken wife, Lucie Fairweather, bravely decided to continue the renovation project in honour of her late husband.
McCloud applauded her resilience, while explaining how Lucie managed to pull off the mammoth property makeover.
He said: "She and her young husband in their late 20s were going to build this beautiful little chalet bungalow with amazing architecture – he was a sustainability campaigner; she’s a teacher.
"On day one, he announces on camera that he’s got stomach cancer.
"He passed away six months later, and we had one day’s filming in the can. And then 18 months later, Lucy rang up and said, ‘I’m going to do this by myself’, with her two children.
"She did it with architect Gerry Tate, who held her hand through the process, guided her through it. Sometimes you don’t know where [a situation] will go, and it can turn such a positive corner."
Lucie and Gerry went on to win an award for their impressive new build which they completed in the wake of losing Nat.Featured Image Credit: rune hellestad/Corbis/Getty Images/Channel 4