A Whangārei home destroyed after a speeding car crashed through its roof had been hit three times before by vehicles flying off the same stretch of road, a relative of a former owner says.

She fears it will happen again and is urging the council to build a crash barrier or realign the road, before luck runs out and someone is killed.

Around 11pm on Tuesday a car police say was travelling at high speed left Mill Road, smashed through a fence, sailed over one unit on Millers Lane and landed on another.

The car crashed through the roof into the living room, which was completely destroyed.

Police said if the owner hadn't been away that night - his partner said he was in his 80s and in hospital at the time - he almost certainly would have died.

A relative of the unit's previous owner, who did not want to be named, was distressed to learn of the latest crash.

"I'm really upset to see it's happened again, but I'm not surprised either," she said.

The woman said one of her relatives was a previous resident of the Millers Lane unit.

She had enjoyed living there for many years, despite the unit being hit by cars three times.

On two occasions damage was relatively minor but a 2018 crash demolished part of her bedroom and could have been fatal if she had been home at the time.

After that crash the family lobbied the Whangārei District Council for a safety barrier on Mill Road, spoke to council engineers, and made direct contact with then mayor Sheryl Mai.

"We kept going back and saying, 'What are you doing about it?'"

The woman said council contractors resurfaced the road to improve grip, and engineers told her they were going to look at the corner because that seemed to be part of the problem.

"I don't think houses should have been built there in the first place. They need to try to build a barrier or realign the corner," the woman said.

Council transport strategy and planning lead Nick Marshall said staff investigated options for reducing crash risk in 2019.
A crash barrier was considered, but building one that was effective would be difficult due to the complex geometry and steep slope between Millers Lane and Mill Road/Whareora Road.

The road would need to be widened and a retaining wall built to allow the guard-rail to fit, and the footpath on Whareora Road would need to be relocated.

"In short, there's not enough ground at the edge of the road to hold up any barrier without building significant foundations," he said.