Its latest Tender Price Index shows that prices rose by almost 4% in the first half of 2018.
The society forecasts that prices will rise by 7.4% in the year as a whole, which is almost half a percentage point more than it predicted at the start of the year.
Such a rise would bring construction prices back to levels last seen in the first half of 2006 and just below their peak in early 2007.
The society warns this could be a particular concern for authorities receiving tenders for national projects, as there is potential for contractors to run into financial difficulty mid-project.
“If the current trend continues prices will be back at the peak boomtime level of 2007 early next year. The current rate of increase is simply not sustainable in the long term,” said Des O’Broin, president of the SCSI.
“The major reason cited by SCSI members for the continuing increase in tender prices is ever increasing workload coupled with the skills shortage being experienced by both main contractors and specialist sub-contractors.”