A few simple building rules could have saved billions of dollars and kept thousands of people in their own homes after the Canterbury earthquake, Far North Mayor Wayne Brown says.
Mr Brown, an engineer with experience in earthquake damage assessment, was one of a 12-strong engineering team inspecting the worst-hit homes in the Christchurch suburbs in the wake of the February 22 quake.
The outspoken mayor has written a five-page report slamming "laughable" building regulations and the poor performance of some popular materials.
Mr Brown went as far as saying brick or masonry veneer walls should be banned after they "fell off in their thousands". Timber-framed houses should instead be clad in weatherboards which were lightweight and flexible.
The same applied to heavy roof tiles and brick chimneys which came crashing down through ceilings, creating more damage and endangering people below.
Corrugated iron roofs, on the other hand, performed well and kept people inside safe even when chimneys collapsed.
If the quake had struck at night many would have been killed in the suburbs by falling bricks and tiles.
"Why not ban both and use iron roofs and steel chimney flues?" he asked.
The engineers had been shocked by some of the "appalling practices" exposed by the quake. Among them were unreinforced blockwork, timber frames not connected to foundations so houses simply slid off their footings, and houses built "foolishly close" to clifftops.
The solution to the latter was to enforce esplanade reserves along the top and bottom of cliffs, in the same way developers could not build right next to a stream.
The problems showed the complicated building codes of recent years were no help, because they were ignored or not understood.
The excellent performance of old timber-framed, iron-roofed homes - built in the decades after a swarm of earthquakes in 1859-70, long before modern building codes - proved his point, he said.
Mr Brown was concerned by the insurance industry's shift to replacement cover, as it seemed unwise to replace failed brick veneers and tile roofs with the same materials.
It was better instead to reclad damaged homes in weatherboards and corrugated iron roofs, which also had the advantage of getting people back into their homes quickly.
Overall Operation Suburb was successful and visited and reported on 18,000 homes a day.
Between the September and February earthquakes, however, an unknown bureaucrat had altered the system of red, yellow and green cards - signifying dangerous, damaged and okay buildings - by removing the yellow option.
That put pressure on inspectors because it left them only with the "nuclear option" of issuing a red card, Mr Brown said.
Civil Defence Minister and Northland MP John Carter tried to reinstate the old system but had been thwarted, Mr Brown said.