A new state fire regulation taking effect today evokes Westborough Fire Chief Walter Perron's memories of a mulch fire here March 11.

Residences with six or more units now cannot have mulch within 18 inches of combustible exteriors of buildings.

Perron said Thursday he supports the change, citing fires such as the one at the Flanders Hill apartment complex on Homestead Boulevard.

"We got down there, and the whole side of the building was completely engulfed in fire," Perron recalled.

"Somebody had thrown a cigarette in the mulch that was right up against the vinyl siding of the building. It went right up the side of the building, and then got into the building. It was a pretty roaring fire when we got there."

The new regulation is "a great law," Perron said.

"We've had some pretty major fires across the state caused by discarded cigarettes and mulch. Some of them have been multi-million-dollar losses," he said.

"As I tell other people I talk to, we're very fortunate in Massachusetts that we have a very proactive state fire marshal, Steve Coan, who is usually ahead of every other state when it comes to safety regulations. And we have a very good board of fire prevention regulations, too."

Most mulch fires in Westborough are "nuisance calls," Perron said. "We go out with a truck and put it out really quickly."

The fires happen because "mulch does look really nice. Landscapers love using it," he said.

"But, people love to toss cigarettes out a window. And mulch is ignited very easily," he said.

"Mulch does look really nice. Landscapers love using it. But, people love to toss cigarettes out a window. And mulch is ignited very easily."

Westborough fire officials inspecting these buildings will check to see if they comply with the new regulation, Perron said.

"Believe it or not, when we show up and problem, people usually appreciate the suggestion," he said.

"It's not a real cost issue at all."

Perron said his one concern with the law is that it doesn't apply to single-family homes.

"I personally don't think that the regulation is strong enough," he said.