The tribunal said the fitout was good, with high-quality modern fittings.
One tenant was a refugee and the landlord helped him get financial help from the Red Cross.
And in late 2020, that tenant and another one moved into the converted garage and agreed to pay the landlord $300 per week.
"For a while, the tenants and landlord remained on relatively good terms," Tenancy Tribunal adjudicator R Kee said.
"The tenants would sometimes go to the main house for meals, and the landlord regularly visited the tenants in the converted garage."
But the good times did not last long.
"The tenants tired of the landlord always coming over. They felt he stayed too long and always invited his friends over when they would have liked more space," Kee added.
"Finally, things came to a head. A disagreement escalated to a physical altercation in which one of the tenants' shoulders was fractured."
And after the incident during a Covid-19 lockdown, the landlord evicted the tenants without notice.
"The tenants were left homeless and spent several months in emergency housing as a result," Kee added.
It turned out the converted garage could not legally be occupied as a living space anyway, so the evicted tenants were now entitled to a rent reduction, Kee added.
"The landlord never increased the rent. Nonetheless, he benefited from the tenants' rent payments."
Kee said the garage even had a potentially unsafe gas stove.
"The public interest also calls for a significant rent reduction to discourage tenancies of unlawful premises such as these. The gas cooker may have caused a greater risk of fire."
The tribunal ordered one-third of all rent paid to be reimbursed. That amounted to $4828.57.
The tenants' claim about a leaking stove was dismissed.
Kee said there was no doubt the landlord evicted the tenants without notice.
"As a result, the tenants were left on the streets and ended up in emergency housing. They ended up living with other homeless people in shared accommodation in the central city for about three months."
Kee said the landlord must pay the tenants $2500 each in compensation for emotional harm.
Kee said the landlord even turned off the electricity at least twice when he was irritated with the tenants.
"The landlord intended to annoy the tenants. The tenants had a hot and uncomfortable night without air conditioning and the food in their refrigerator spoiled."
Kee ordered damages of $450 be paid for that.