The Canberra Times on Friday reported Mr Ramsay had this week approved a measure to allow the ACT to hold off on adopting the 2019 Building Code of Australia until September 1.

It came despite all other states and territories signing up to the code on May 1.

Mr Ramsay defended the decision on ABC radio on Friday morning, saying each jurisdictions had a different approach to ushering in the new standards.

He said the "relatively short time frame" between the code's preliminary release in February and expected adoption date on May 1 meant it was "more difficult to make sure that everyone had the same level of information."

A government statement explaining Mr Ramsay's decision this week said the three-month window did not give owners and practitioners enough time to amend designs for planned projects to ensure they complied with the new standards.

The 2019 code includes extra requirements for fire sprinklers in apartment buildings four storeys and above, revised energy efficient targets for commercial blocks and added provisions for condensation management.

Mr Ramsay said the decision had been informed by the industry's views on how best to transition to the new code, which was being updated for the first time in three years.

But that claim was again challenged by Master Builders Association of the ACT chief executive Michael Hopkins, who said he was "caught by surprise" when informed of the delay on April 30, a day before the new code's expected adoption date. The Australian Institute of Building Surveyors' ACT branch also confirmed it first learned of the delay on April 30.

Mr Hopkins told ABC radio that he was concerned the government's decision would cause confusion for builders and contractors who work in the ACT and NSW.

"There'll be builders working with two sets of laws," Mr Hopkins said.

Owners Corporation Network president Gary Petherbridge slammed the decision, arguing it could trigger further delays to the implementation of the ACT government's own, long-awaited building quality reforms.

"We're the only jurisdiction that has a building quality minister, so I'm surprised that we cannot get our act together," Mr Petherbridge said.

"It is extremely disappointing. As for consultation, I attempted to have a meeting with the minister about three or four weeks ago and that was refused. I did meet the chief of staff, but generally the access to the minister is very poor."

"From a consumer advocate's point of view, this is very, very poor form of activity that they are doing. It has not been handled well at all."