Francis Tomney and his sons Francis Tomney Jnr and Thomas Tomney, from Blackpool, carried out work on driveways across the north-west and in Hertfordshire.
In one case a pensioner was made to hand over £31,000 for work the Tomneys claimed they had done at her Blackpool home.
An 80-year-old victim from Stockport was told chemical sealant was being poured on to his driveway when in fact they used milk. The gang told the pensioner to keep cats away as they might get poisoned by the liquid.
Sentencing the trio at Preston Crown Court, Judge Michael Byrne said: “I am satisfied that on each occasion of these transactions they saw the customer as an opportunity to make money but the practices used to further this aim amounted to dishonest and fraudulent conduct in each case.”
Francis Tomney Snr, 55, was jailed for five-and-a-half years, Francis Tomney Jnr, 21, for five years and Thomas Tomney, 21, was imprisoned for four-and-a-half years after they they all admitted conspiracy to commit fraud.
All three pleaded guilty at an earlier hearing.
A fourth man, cousin Brian Tomney, 29, was jailed for 15 months for fraud and cheating the public revenue.