A strike by crane operators will escalate from Friday when pickets will be placed on sites belonging to firms represented by the Construction Industry Federation.
Up to now the strike, organised by the Unite trade union, which says it represents 170 crane operators, had only hit affected operators employed by non-CIF agencies and firms.
That element of the industrial action resumed this morning with pickets on the Gem site at the Bridewell, though a number of other sites have also been hit over the past ten days.
Two further Dublin sites will be picketed tomorrow.
However, Unite has now confirmed that the stoppages will spread to CIF firms on Friday, potentially halting construction work nationwide.
Most sites cannot do normal construction work without the crane operator, and additional disruption would flow from a refusal by other workers to pass pickets.
The CIF has described the Unite claim as unsustainable and irresponsible.
In today's statement, Unite criticised CIF Director General Tom Parlon for describing Irish cranes as "Mickey Mouse" compared to other cities, and for saying that operating a crane was "not rocket science".
Regional Secretary Jimmy Kelly said that while construction profits had doubled since 2012, wages were still below 2004 levels in real terms.
He said members were determined to ensure that construction workers shared in the sector's recovery, and that crane operators' wages reflected the level of skill and responsibility involved in the job.
He accused the CIF of refusing to engage with the union, and said Mr Parlon's comments had simply hardened the resolve of members.
The dispute is further complicated by an inter-union row between Unite and SIPTU who traditionally represent the crane operator grade.
SIPTU has lodged a formal complaint about Unite with the Irish Congress of Trade Unions, and the result of that disputes committee hearing is expected next week.
Earlier this year, SIPTU had secured two hours additional pay per day known as "greasing time" for the crane operators, which they said was equivalent to a 25% hike.
In addition, negotiations are under way between the group of construction unions and the CIF on a new legally binding Sectoral Employment Order to set statutory minimum pay, pension and sick pay rates across the construction sector.
Divisional Organiser Greg Ennis said his union was awaiting the outcome of the SEO process which involved a claim for all construction workers, not just a single group within the industry.
He has previously called for a review of all construction pay rates for all grades, which are currently set through a relativities process.
