Mr Arthur, a farmer, said he hired Mr Toon in 2004 for a job which was meant to take 13 weeks and ended up lasting more than 36.
As the builders prepared to finish the job the Arthurs discovered a gas leak and their architect and project manager banned Mr Toon from the site.
"I was more than patient with him but the final straw came when a gas leak was discovered. When I told him he simply said 'open the windows'," he said.
"The work he carried out was defective and incomplete. Concrete paths had not been laid properly and the rendering to the exterior was poor.
"The toilets hadn't been plumbed in, there were no doors on the shower and no stove in the downstairs living room, along with other things too numerous to mention."