Only a "sliver" of the entire Canterbury earthquake reconstruction work has been undertaken so far; which includes $334 million paid to sub-contractors to repair homes and the demolition of 719 buildings to date; two-thirds of them in the Christchurch central business district.
The full, positive impact of the rebuilding of Christchurch has been pushed out until the end of this year or early 2013 by some analysts.
"We forecast a strong pick-up in building activity, starting soon," Mr Ebert said in a statement from recent research.
Of $11.8 billion of consents issued between September 2010 to December 2011, only 2.2%, or $259 million was related to Canterbury earthquake work.
"There is a mammoth quantum of [Christchurch] reconstruction that still needs to be done, in the end," Mr Ebert said.
Because of the most recent December quakes, the BNZ had pushed out its rebuilding pick-up profile by a further three months, mirroring estimates of the Reserve Bank.
While building consents had been trending upward, it was slowly, which had not been assisted by "the trickle, rather than flood" of consents related to Christchurch, Mr Ebert said.
He said revisions of the value of damage/stimulus work, including by Treasury and the Reserve Bank, had totals around 10%-15% of GDP, noting that "only a sliver of which has come to bear so far".
The EQC disaster fund had written down all of its $6 billion of assets it had before the Canterbury quakes.
"That's a total of $20 billion of funds right there, equivalent to near enough 10% of GDP," Mr Ebert said.
New Zealand's construction sector is expected to pick up noticeably during 2012 and next year, led by residential activity this year up 25% on the previous year then a 31% gain during 2013, Mr Ebert said.
Non-residential (commercial) would "eke out" only a 3% gain this calendar year, but should see a stronger showing next year with a 12% gain.
"The more delayed [non-residential] profile has something to do with the longer timeframe for commercial redevelopment in Christchurch," he said.
`Other' construction activity is dominated by public infrastructure, much of it roading. Mr Ebert predicts 3% growth this year and 6% during 2013.
The growth predictions for the construction sector overall equated to 11% expansion this year and 17% for 2013, which would greatly support GDP through to end of 2013.
