The fires took a total of roughly five hours to extinguish, but because neither was occupied and both were in very poor condition, there wasn't a damage estimate, Modesto Regional Fire Authority Battalion Chief Cecil Ridge said Monday.
The first broke out at 9 p.m. Sunday at Santa Cruz and Larkin avenues.
"It was in poor condition, with a large amount of debris in the yard," Ridge said.
Firefighters from Modesto Regional and Stanislaus Consolidated attacked the fire to keep it from spreading to a residence in the back. They were on the scene about two hours.
The property is across the street from — and owned by — the Gallo winery, Ridge said. The buildings had been slated for demolition.
The second call came in at 12:14 a.m. Monday, at 713 Imperial Ave. That home had burned at least once in the past year, Ridge said.
"The house probably should have been bulldozed," he said.
Firefighters were on the scene roughly three hours to put out the blaze and keep it from spreading to other properties.
It's not clear what caused either fire. Neither property had electrical service. Ridge termed both fires "suspicious" but said they burned so completely it was hard to tell if squatters had been staying there. "That's occasionally a problem we do have," he said.