Aaron Gourlay (43) was acquitted on five of six charges which were the subject of an eight-day jury trial in the Dunedin District Court.
The jury found him guilty on one charge of arson, relating to the car of a former workmate.
Gourlay had denied six charges, the Wastebusters arson, three car fires and intentionally damaging the tyres on two cars.
The cars all belonged to former work colleagues and Gourlay's former partner.
The jury spent a total of eight hours deliberating, five hours on Wednesday and another three yesterday, before returning their verdict just before noon.
Judge Kevin Phillips discharged Gourlay on the five charges on which he was acquitted and remanded him for sentence on the one car arson of which he was found guilty.
A sentencing date has yet to be confirmed.
