SIPTU members have joined with construction workers from across the EU at a protest in Brussels calling for an end to exploitation in the sector.
Today's demonstration was held to urge the European Commission to take action to limit and curtail breaches in sub-contracting chains.
It is part of a wider campaign by the European Federation of Building and Woodworkers (EFBWW) with which SIPTU is affiliated.
The EFBWW has 77 affiliated unions in 36 countries and represents 1.5 million members.
"Often, companies use sub-contracting chains to disguise employment relationships, circumvent tax and social security payments and hide from controls by labour inspection bodies," said SIPTU Division Organiser Adrian Kane.
"Sometimes, sub-contractors vanish without paying the workers the wages due to them after months of working. It is time to put an end to this," Mr Kane said.
European trade unions say that long, complex chains in sub-contracting are a major risk factor for the exploitation of workers.
They are calling for EU legislation to ensure that member states set rules to limit sub-contracting levels in public procurement projects.