The Royal Bank of Canada building evacuated after a hydro vault exploded beneath it earlier this month will remain closed for at least six months, CBC Toronto has learned.

A series of blasts echoed along King Street West around 5:15 p.m. on May 1, at the start of an electrical fire beneath Toronto's central business district.

No one was injured, but the RBC building was evacuated at the time. And employees just learned this week that they won't be back for months.

Royal Bank of Canada employees will not be allowed back in the building for six months, the bank says. (Michael Charles Cole/CBC)

The bank's senior vice-president and global head of corporate real estate informed workers that 20 King St. W. will be closed for business for at least six months, according to an email obtained by CBC Toronto on Tuesday.

"Due to heavy contamination from soot residue in the building, it is not possible for employees to return to the building to retrieve their laptops or files … or personal effects," Nadeem Shabbar wrote.

Workers have been moved to other RBC locations since the fire and the bank is considering renting another property for a short time, Shabbar said.

Instead, restoration crews are trying to collect both the company's equipment and anything else left behind by employees during the evacuation.

"Any equipment or items that are irreparably damaged will be itemized and photographed so that insurance claims can be made."

Many insurance claims expected: RBC

Shabbar said he expects it will take between four and six weeks for employees to get anything returned to them, describing both the cleanup and the insurance fallout as "a lengthy process."

A spokesperson from RBC could not be immediately reached Tuesday evening to discuss whether the bank's insurers had contacted Toronto Hydro about filing claims. Catherine Hudon later sent a statement confirming that the building would not be used for the next six months.

The utility, meanwhile, has not yet completed its investigation into why the hydro vault — which includes high voltage transformers — exploded. Spokesperson Tori Gass said Tuesday that it could be some time before Toronto Hydro would have those answers.

Crews remove the charred transformer destroyed in the May 1 hydro vault fire and explosion. Toronto Hydro has not said what caused the fire. (CBC)

The explosion, however, came on the heels of several days of heavy rain. Both the utility and Toronto Fire Services confirmed that a "significant" amount of water had leaked into the vault and had to be pumped out on May 1.

The explosion and subsequent electrical fire created "three levels of soot going down to the sub-basement and there was a significant amount of damage in the transformer room," Toronto Fire Services Platoon Chief Kevin Aucoin told CBC News earlier this month.

Gass said Toronto Hydro has not inspected the rest of the building to assess that damage.

It's unclear if the transformer was affected by the water that seeped into the hydro vault. (CBC)

​What a fire leaves behind

Toronto Fire Capt. David Eckerman said toxins can continue to be released from materials long after they've burned.

While Eckerman didn't want to speak to the specifics of the RBC building, he said that the synthetic materials favoured in construction release carcinogens if burned.

"They may bond with other compounds that are being released and create a completely different compound and it's extremely toxic," he said. "You'll have smoke migration within a building and all this stuff has to be remediated.

"It's known to be cancer-causing and you can't just have that residue in office space, on walls, in carpeting and so forth."