Attorney-General Simon Corbell dismissed the need for a wide-ranging inquiry proposed by opposition treasury spokesman Alistair Coe, saying the Liberal Party should conduct its own policy development and not undertake stunts in the assembly chamber.

''Our planning system is a very comprehensive one and the government has announced a series of reforms to provide support to the construction sector,'' Mr Corbell said after government MLAs voted down the proposal.

''Changes to lease variation charges, extensions of time fees [and] new civil works packages for new residential estates are all designed to help our construction industry at this difficult time.

''The key issue that the Liberals are ignoring when it comes to the construction sector is the enormous damage being done by Tony Abbott's job cuts to Canberra.''

Mr Corbell dismissed the motion as a ''grab bag of ideas''.

''Given the seriousness of this proposal, it was incumbent on the Liberal Party to do their homework and to try and lobby more broadly about the need for such an inquiry,'' he said. ''They failed on both counts.''

Broad terms of reference put forward by Mr Coe called for consideration of government agencies involved in the sector, its contribution to the ACT economy and the state of industrial relations in the territory.

The inquiry chair would have been chosen through an agreement between Chief Minister Katy Gallagher and Opposition Leader Jeremy Hanson.

Construction, Forestry, Mining and Energy Union ACT secretary Dean Hall said Mr Coe wanted to see a reduction in safety regulations and pay for construction workers. ''Alistair Coe and the Liberals should probably come out with the real agenda,'' he said.

''They want construction workers and their families and communities to have significant reductions in their standards of living by reducing not only their safety but also their pay and conditions. They should just come out and say they want construction workers to be paid less.''

Mr Coe said the government had missed an opportunity to assist the construction sector.

''The release of land, compliance charges and endless red tape are major issues for the sector and many businesses are being driven across the border,'' he said.

''Often, Canberrans trying to own their own home are hit with the flow-on costs borne by the industry. It's disappointing the ACT Labor government hasn't taken the first step to understanding the issues affecting the overburdened construction sector in Canberra by failing to vote to appoint a board of inquiry.''