The Enquirer has been contacted by a number of firms who have equipment locked-in on former GB jobs.
And the stunned subcontractors have been threatened with police action if they try and take back their own kit.
Security teams acting for the administrators of GB padlocked the gates of sites across the country last week.
One supplier said: “We are a subcontractor but we have over £60,000 worth of equipment on four of their sites that we are not allowed access to.
“Security on site threatened to call the police if we take our own equipment.
“We are also owed thousands in unpaid invoices so this is a double whammy.”
Another company boss said: “I’ve got some of my platforms on their jobs and we aren’t allowed on to get them.
“There’s something very wrong when you can’t go onto a site and claim back what’s rightfully yours.
“On one of their jobs we were hiring the kit so are still having to pay hundreds a week in fees on something we can’t use or give back to the hirer.
“The whole situation is a sick joke.”
A spokesperson for the Joint Administrators said: “Control of all sites was transferred back to the site owners after the Administration was confirmed, and security arrangements have been put in place by the site owners.
“Subcontractors with equipment remaining on site should get in touch with the site owners’ appointed representatives to arrange a suitable time for collection.”
Legal expert Julian Saunders said subcontractors should not be scared off by warnings of police action.
He said: “If the subcontractor has terms and conditions which reference to ‘hire of materials’ for the contract or the ‘plant hire model terms and conditions’ then if they attend site to recover with the paperwork evidence the police will not take action.
“They will view it as a civil case and inform the security teams that is the case.”
The news comes as the Enquirer continues to be inundated with horror stories from subcontractors about GB’s poor payment practices.
One said: “Without fail the payments to us were late .
“Every month a seven day notice was sent to GB and this happened across the whole site with every subcontractor.
“Their accounts department were just a constant string of excuses.”