A Fire and Emergency New Zealand spokesperson said emergency services were called to Blast and Coat on Miller St, at about 6.45am, on May 10.
Blast and Coat owner Rowan Huxford said the fire had started in a workshop but no paint or chemicals were stored there.
He said he and some other employees had been working in another workshop when the fire occurred.
He remained philosophical, even as the clean-up began. At 2pm on the day of the fire, he said he was busy trying to plan a way forward so that his workers have activities to be going on with. "We'll get there," he said.
Miller St was blocked off just past the corner of Easton St and anyone driving towards Weber was diverted up Makirikiri Rd.
Plumes of smoke and some flames could be seen from the intersection earlier that morning.
There was an unmanned fuel stop on the opposite side of the road, which appeared to be at little risk from the fire. The fire service reported just before 11am that morning that the fire was extinguished and crews remained at the scene to mop up and check for hot spots.
A fire investigator was also on the scene during the morning. No one was hurt in the blaze.
