An unstable and fire-damaged wall will remain in place when fire investigators begin their painstaking work of trying to figure out how a Hamilton business was reduced to ashes.

The delay in determining the cause of Monday morning's blaze at AH Franks Tyres is due to the large amounts of asbestos that was in the roof cladding.

The fire is being treated as suspicious until investigators can prove otherwise, especially as Monday's blaze was the second in 24 hours and the third in four years at the site.

Seven employees now face an uncertain future as owner Jim Nolen is left with only a pile of ashes and the charred remains of several vehicles that he was working on.


Waikato senior fire risk manager Kevin Holmes said the roof's remains contained asbestos and this afternoon that was being swept up by workers at the scene before being packaged and sealed for disposal.

The asbestos was left all over the the scene including across an adjacent driveway.

Holmes also said investigators will leave the dilapidated southern wall in place despite it being 'bowed', as the steel beams holding it in place appeared strong enough to hold up for when they make their way through the scene tomorrow morning.

The concrete wall will eventually be pulled down, while the fire wall - which separates AH Franks from Collins Auto Electrical next door - will also need to be checked out and replaced if necessary.

The blaze was so big that at its peak, the massive clouds of smoke could be seen from as far away as Raglan.

The smoke could also be seen from the air and plane passengers took photos of the scene from the sky.

Holmes said wet asbestos was okay but when it dried it became toxic and the dust could float through the air.

Asbestos can cause severe health risks if inhaled and it needs to be removed carefully.

Workers charged with the job today were fully covered and wore breathing masks, boots and boiler suits.

The scene has been cordoned off and was under police guard this morning.

Throughout yesterday's firefighting operation, firefighters were being hosed down and their uniforms thrown in bags for washing because of possible contamination.