H&B representatives from Bovis Lend Lease's Paternoster Square site, St George's Vauxhall Bridge development and Amec's Victoria House Holborn project attended the meeting in central London.
Union UCATT said the firm must honour the Working Rule Agreement for holidays. This stipulates that workers are entitled to 21 days paid holiday, in addition to all bank holidays.
Union official Mick Dooley said: "It seems that the only way to close the issue of holiday pay is the close of the job." H&B denies that it has broken the agreement.
The men will now conduct a postal ballot over industrial action, the result of which will be known next month.