Mortgage brokers have seen residential mortgage refinancing shoot up in the region this year as homeowners try to take advantage of historically low interest rates. Sometimes, more than once. Call them “serial refinancings.”

The trend has been under way all year.

Chris Howell of Academy Mortgage Corp. said he has been helping borrowers find lower rates for their home loans for months.

Many of those refinancing did so just a couple of years ago, Howell said, bringing their interest rates down to 4.5 percent. At the time, mortgage professionals thought the rates couldn’t get any lower.

Of course, rates continued to fall and those who thought 4.5 percent was good in 2011 thought 3.5 looked even better, Howell said.

In some cases, brokerages are able to cover the closing costs on a refinance, making the idea even more attractive to homeowners, according to Howell.

“Usually a 1 percent drop is worth refinancing, but if the closing costs are covered, a half-percent drop is worth it as well,” he said.

Howell said he last saw this type of activity in the early 2000s.

Jim Hunter of Cornerstone Mortgage called it “phenomenal