Have ice dams on your roof after the snowstorm? Here's what to do, according to an expert.

Roof cleaning companies in Massachusetts are working overtime to remove ice dams from homes, several days after the biggest snowstorm here in nearly four years.

What is an ice dam?

Ice dams are caused by the warming and freezing cycles of snow on a roof. That snow starts to melt; the water freezes again and causes a dam.

"When it melts, the water comes down, has nowhere to go and kind of creates a little bit of a dam and then the water works its way up your roof, which is what you don't want," said DJ Warila of Green Monster Roof Cleaning, which services central Massachusetts.

"We've seen it come inside people's homes, down their ceilings. You can't really see exactly the damage it's causing until you open it up. A lot of times, you'll see the soffit leaking icicles, which means the water's getting in the house. Oftentimes, skylights will get damaged or dormers where there's any type of seam in the roof. It can just get in and cause water inside the house."

Jennifer Martinez, a homeowner in Shirley, had 22 inches of snow on her property after the storm. Days later, she noticed what looked like shadows on a ceiling in a room in her home.

"We could see water dripping down here a little bit, so we immediately we figured we had an ice dam," she said. It was, according to Warila.

Ice dam removal

If you have an ice dam on your roof, don't panic, he said. There are things you can do yourself to be proactive. Start with a roof rake.

"Just remove the heavy snow and then go ahead and leave some roof melt pucks up there to create channels for the water to make its way out," he told WBZ-TV.

"It's not always the big ones you're concerned with. Sometimes you don't even see the ice dam under the snow."

But if you're not able to get on or near your roof, call a professional.

"Hire a company that's insured," Warila said. "If anybody thinks about stepping foot on your roof, you might want to make sure they are a roofing company, a roof cleaning company. Often times landscapers and other companies do carry insurance, but it might not be the proper insurance."

Warila said his company saw a lot of ice dams about ten years ago in that historic winter. They were removing them then up until early April.

Ice dam prevention

To prevent an ice dam on your roof, experts said there are a few things you can do ahead of time.

It can help to install heat cables in your gutters and put proper insulation in your attic.

You should also clear your gutters in the fall before it snows.

Once a storm ends, use a roof rake to pull the snow off the edge off the roof and throw some roof ice melt pucks up there.