A raid by immigration officers in east London discovered a bedroom converted into a fully-equipped factory manufacturing British, European and Indian documents.
Snaresbrook Crown Court heard that the men were all involved in creating and distributing between 50,000 to 100,000 false documents including passports, driving licences and Construction Skills Certification Scheme cards.
CITB supported the investigation by supplying evidence on genuine CSCS cards and verifying the status of counterfeit cards and qualifications that had been produced.
Sandeep Singh and Harjinder Kingre, both of Leigh Road, East Ham, denied their role in running the bedroom operation, but a jury convicted them both of conspiracy to make and supply articles for use in fraud. They were each jailed for eight and a half years.
Pritpal Singh admitted his role in the plot, along with another charge related to possessing one of the fake passports, and was jailed for six years.
Satnman Hayer of Normanton, Derby, and Gurjit Singh of Southall, Ealing, both admitted to buying forged documents to sell on for profit.
Hayer was sentenced to three years and nine months in jail while Singh will face sentencing at a later date.