By Chris McKinnon, WBZ-TVBy Chris McKinnon

BOSTON (CBS) — Building permits are designed for safety, but the I-Team has learned thousands of Massachusetts homeowners and landlords are doing work illegally.  It’s a gamble that can have disastrous results.

Bill McCarthy knows just how bad it can be.  He was working on a porch with another man in Jamaica Plain last year when the structure collapsed.

READ MORE: Breaking And Entering Suspect Caught On Camera In Brookline

“We both fell,” he recalled.

“I looked over the edge when I got to my feet and I seen Steve laying there on the ground,” he said.

Steve was killed.

It was a tragedy that may have been prevented if the project had the proper permits. The homeowner did pull a repair permit, but the project was structural, which requires a different permit and much closer scrutiny by city building officials.

A porch under construction in Jamaica Plain, where workers fell. (Photo credit Carl Stevens/WBZ

A porch under construction in Jamaica Plain, where workers fell. (Photo credit Carl Stevens/WBZ

“We offer an expertise in construction and building,” explained Boston Inspectional Services Commissioner William Christopher.

“That gives an extra set of eyes to make sure that things are being built properly,” he said.

The I-Team obtained documents that show Boston inspectors wrote 398 violations last year for building without a permit.  That’s up more than 10% from 2013.

According to Newton general contractor Cindy Stumpo, this kind of thing happens all the time.

READ MORE: Hopkinton High School First In State To Drop Mask Mandate

“Your life is on the line,” she said explaining that without the permit, there is also no inspection to make sure the work was done right.

“So the plumbing inspector never came out to check and make sure your gas dryer is hooked up properly, that your gas stove was hooked up properly. Who’s covering your back,” she warned.

The I-Team sorted through pages of permit violations and found many of these offenders are landlords, people who Boston Inspectional Services Commissioner William Christopher says are usually well aware of the rules.

“We’ve had some people who are chronic offenders,” he said.

Uwa Lawrence is one of those chronic offenders.  Boston ISD staff issued Lawrence six citations for building without a permit, more than any other property owner.  Many were large structural projects like removal of large portions of foundation.

Not pulling a permit can have other risks that may not be as obvious as cutting corners with structural work to your home. For example, if a homeowner has a leak in an area of that was renovated without a permit, the insurance company  may not cover the cost to repair the damage.  Selling a home could also be trouble if you’ve had work done without a permit. Permits are public record so any potential buyer could pull the permit history and if it’s obvious there is unpermitted work in the house, it could kill the sale.

Experts agree that safety is the number one concern.

“When it comes to safety, there are no cutting corners,” Christopher said.

It’s a painful lesson for Bill McCarthy who lost his best friend in that porch collapse.

MORE NEWS: 'Our Kids Deserve Better': Photos Show Spoiled Meals Served To Lynn Elementary Students

“I’m a mess about all this.  I loved that kid like a brother,” he said.