Plumbers, fitters, welders and apprentices who are members of the Unite trade union are again picketing a number of construction sites around the country.
It is part of a campaign seeking the restoration of cuts to the first hour of travel time implemented during the period after the financial crash in 2008.
It is the second Friday running that the workers have engaged in strike action over the issue.
The locations being picketed are construction projects by pharma company Pfizer at Grange Castle in Dublin and Ringaskiddy in Cork.
The pickets are not aimed at Pfizer, but at members of the Mechanical Engineering & Building Services Contractors' Association (MEBSCA) who are carrying out works at the locations at present.
MEBSCA has called for an end to the picketing and a return to a collective talks process.
It warned that continued industrial action by Unite will result in reputational damage to the sector, which could ultimately result in job losses.
MEBSCA has previously said that the first hour of travel time has been incorporated into hourly rates since 2011 as part of an agreement reached with Unite.
It said the agreement had the effect of increasing the hourly rate which also resulted in a higher rate being paid for overtime and holidays.
The association has claimed that Unite is now seeking to maintain the higher rate of pay while also seeking to reverse the agreement that was freely entered into by Unite at that time.
"MEBSCA is extremely disappointed that its member firms are yet again being targeted by Unite for additional increases in pay approximately eight months after an agreement on pay was negotiated with the union," it said.
"This agreement does not expire until May 2026. This current claim by Unite is for the "restoration of the first hour of travel time" which was incorporated into hourly rates in 2011 by agreement with Unite."
"The union is claiming that the 2011 agreement was a temporary agreement, despite the fact that when the current pay agreement expires, hourly rates will have increased by almost 32% since 2011."
MEBSCA added that members pay a travel allowance on top of pay.
The pickets began at midnight and will run for almost 24 hours.
Last week, construction projects for major companies including Intel, Diageo, Eli Lilly, Analog and the ESB were hit by a 24-hour work stoppage.
