Other finalists include specialist bra-fitter Joanna van Blommestein, who built lingerie boutique Bra Boss in her summerhouse.
Isle of Wight resident Nicholas Pointing built a Chitty Chitty Bang Bang-inspired shed, as he wanted a space to construct a replica of the film’s car for his wife.
In the Nature’s Haven category, Herefordshire archaeologist Rebecca Roseff built a medieval-inspired shelter to support rare horseshoe bat colonies for their summer roosts.
Hundreds of entries were whittled down to a shortlist of 22 over nine categories, with the winners decided by a public vote. Voting opened on Wednesday and will close on July 12.
The overall winner will receive £1,000, a plaque, £100 worth of Cuprinol products and “eternal shed glory”.
Andrew Wilcox, head judge and founder of the competition, said: “The past year has been an incredibly challenging time for all of us and, now more than ever, we’re aware of how important the humble shed can be.”
Mr Wilcox went on: “Sheds are not just unloved, brown structures at the bottom of the garden that house tools and household junk – they are vital spaces where you can go to relax, work on a project or burn off some steam.
“The high-calibre entries this year really prove why we set up the competition in the first place – to highlight the valuable role sheds can play in our lives, in our businesses and the positive impact they have on our wellbeing.”
Last year’s winner was Daniel Holloway, who created a nature-inspired Bedouin Tree-Shed, built around two tree trunks in his back garden.