Johnny Carroll, 26, defrauded 21 victims out of Â£108,000, Exeter Crown Court heard.
He quoted reasonable estimates for work to walls and roofing but once his team was on site the price rocketed and victims were bullied into paying, the court heard.
He admitted a single count of fraud.
Carroll of Cricklade, Wiltshire, used eight different company names and often set up local telephone numbers for just long enough to get business before he closed them down, the court was told.
Two victims have died since giving interviews to police and at least one more has had to hand over their financial affairs to their family as a result of the crime, the court was told.
The building work was carried out from July 2012 to May 2014 in locations including Portishead, Bath, Buckinghamshire, Bristol, Cornwall, towns across Devon and Llangynidr in Powys.
Carroll carried out the crimes while on a suspended sentence for previous fraud.
John Rice, aged 21, of Ceri Road, Swansea, admitted two charges of money laundering and was jailed for 12 weeks for his part in the operation.
The leader of a gang of rogue builders who preyed on elderly people across south-west England and south Wales has been jailed for more than three years.