The Department of Education has ordered random audits of school building projects.
The audit is an effort to ensure that contractors are complying with proper pay and working conditions on sites.
Minister for Education Ruairi Quinn said that the vast majority of building contractors are fully compliant.
However, he said he wants to ensure all workers on sites funded through the Department of Education are getting their proper entitlements.
Ireland is borrowing €2bn from EU and IMF sources to fund the construction of hundreds of new school buildings and education facilities.
Its growing population makes it necessary. But it is also hoped the investment will act as a stimulus to the economy.
Lately, the building programme has been beset by problems, among them concerns that workers are being encouraged into the black economy by a minority of unscrupulous contractors and subcontractors.
Now the Department of Education has appointed a private company to carry out random audits of sites.
It will check pay and conditions, but also be on the alert for potential tax and social welfare fraud.
The department says detailed audits of employment records will also be carried out on a number of projects.
The Irish Congress of Trade Unions has welcomed news of the random audits.
In a statement, ICTU said it has been concerned that unsustainable tendering and procurement practices have been leading to hidden economy activity, runaway contractors and the exploitation of workers.
It said the appointment of auditors will send the right message to would be non-compliant contractors.
However, ICTU said it believes public bodies such as the Department of Education should go further and ensure than tender prices for contracts are sustainable.
It said contractors need to be given the possibility of finishing work without having to rely on cheap, exploited labour.