As a result of this investigation, police are now considering if they will investigate any criminal liability attached to those involved with the building.
But one of those firms has hit back strongly at the DBH report, saying some of its content was "highly questionable" and assumptions made in it "may be flawed".
Alan Reay Consultants did the initial structural design of the CTV building and its principal, Alan Reay, said: "Personally, I feel incredibly torn. I have huge empathy for the families waiting for answers, but these reports are technically inadequate."
Victims' families were shocked by the DBH findings, some wanting police to find who is to blame for the building's collapse. Karen Bishop, whose son Andrew, 33, died in the collapse, said she was disgusted to learn the building hadn't been up to scratch from the beginning.
"Someone has to be answerable for this. For God's sake, it killed 115 people and it should never have happened."
Pyne Gould Corporation (PGC) Building
The collapse of the five-storey PGC building, which housed some of the city's professional firms, left 18 dead and many others seriously injured.
A DBH investigation found lack of strength and flexibility in the 40-year-old building, combined with the February quake's severe shaking, caused the building's core to fail.
The resulting movement of the floors led to failure of the columns and beam-column joints "causing the floors to collapse on top of one another".
In November, the royal commission heard workers and tenants were "repeatedly told" after the September 2010 quake that the building was safe to occupy. Although cracks had been noted, several inspections concluded there was no imminent danger.
The building's owner, Stephen Collins of Cambridge 233, told the commission he had "trusted" estate agents and lawyers carrying out due diligence on his behalf before he bought it.
They had failed to tell him earlier engineers' reports revealed the building had "the potential for severe failure" in the event of a major quake.
"I discovered what had happened... when I was 2500 miles up the Amazon in a boat; I turned on the TV and the first thing I saw was the lady being pulled out with a crane," Mr Collins told the hearing. "It was one of the most horrific things I've witnessed in my life, knowing I owned the building and there had been the loss of life of 18 people and many more hurt."
Christchurch Cathedral
The future of Christchurch's best-known landmark looks grave.
The cathedral has suffered severe structural damage in the quakes over the last 18 months, including the latest big quakes on December 23, and it's proving too dangerous for experts to get inside for a full assessment.
The outgoing cathedral dean, Peter Beck, recently told the Herald that the building's future "is not looking good".
Cathedral project manager, RCP's Marcus Read, told Campbell Live this week that the cathedral was "rocking herself to pieces".
In a statement, Anglican Bishop of Christchurch Victoria Matthews said: "The cathedral is now a very dangerous building and internal access is impossible. We are undertaking new engineering reassessments... to determine what are the realistic options for the building's future.
"When we have a peer-reviewed assessment of the building, we will publicly share that assessment."
A more detailed announcement is expected next month.
Hotel Grand Chancellor
Christchurch's tallest building is being slowly disassembled in one of the most complex demolition projects of its type in the world.
The 28-storey hotel is being pulled down at a cost in excess of $10 million. The demolition is expected to be completed by April.
The building suffered major structural damage a year ago, but all guests escaped unharmed.
A DBH investigation found the extent of the damage was "significantly increased by the collapse of a key supporting shear wall which failed in a brittle manner".
This shear-wall failure had led to a major stair collapse and failure of columns and beams.
The demolition went on hold last month when a worker fell from a ladder and was seriously injured.
A prohibition notice stopping work has now been lifted.
City centre
Aside from the Hotel Grand Chancellor, hundreds of other quake-damaged buildings are being knocked down in central Christchurch.
A central-city red zone is still in place, cordoning off parts of the CBD where many of the demolitions are being done, and there is still danger of further collapses.
The royal commission has so far heard damning evidence about the state of a number of central-city buildings that had contributed to deaths in Christchurch, including a lack of detailed inspections and identification of risks after the September and Boxing Day quakes in 2010.
The revelations have left some victims' families asking who will take responsibility for those buildings still occupied, or remaining a threat to people working nearby, when the February quake hit.
It was hoped the central-city red-zone cordons could be lifted by April, but damage from ongoing aftershocks has put that schedule in doubt.
The suburbs
Suburbs in eastern Christchurch have borne the brunt of the damage, with large swathes of housing in riverside suburbs such as Bexley and Avonside being written off because of the major impact of liquefaction on the land.
Almost 7000 properties are classed as being in the suburban red zone, where it is considered uneconomic to repair the land.
The Government has offered to buy this land at 2007 rateable value, and property owners have the choice of being paid out on dwellings by the Government or their insurers.
Demolition of abandoned homes in the red zone in Bexley began recently.
Some red-zone property owners, such as Brent Cairns of Kaiapoi, do not accept the decision to write off their land and are refusing to budge.
"We are in a far better position just staying where we are. Why should we [take the payouts] and go into debt?" Mr Cairns said.
Hundreds of property owners in the orange zone are still awaiting further findings to see if they can rebuild on their land or will have to start again somewhere new, while hundreds more in the hillside suburbs' "white zone" are still to learn the fate of their land.
The vast majority of Christchurch properties are in the green zone, meaning the land is okay for continued occupation or rebuilding.
Infrastructure
An estimated $2 billion will be spent on rebuilding Christchurch's quake-torn infrastructure.
Underground services, including about 300km of sewer pipes and about 124km of water pipes, are being fixed first before workers move on to the permanent repair of roads - expected to soak up a third of the budget.
Repairs to the sewer network are expected to take up about another 40 per cent of the total.
Many homes were left without running water or flushing toilets after the quake a year ago, but sewage services were returned to all homes by August last year, either by connection to the network or to temporary solutions.
Water supply has also been returned to all homes.
The rebuild of the damaged underground services and roads is expected to take five years to complete.
