The type of plastic-filled exterior cladding implicated in the rapid spread of the deadly London tower fire is permitted in Ontario on buildings under seven storeys.

But Mark Cripps, a spokesman for Municipal Affairs Minister Bill Mauro, said the Ontario Building Code also stipulates that if “combustible cladding” is used on a building over three storeys, the structure must be equipped with automatic sprinkler protection.

“In circumstances where foam plastic insulation is permitted, the insulation must meet stringent fire performance testing to limit the amount of smoke produced and slow the spread of flame, or the insulation must be protected by non-combustible material,” Cripps said in an email.

Investigators probing the Grenfell Tower fire, which killed at least 30 people and possibly dozens more, are looking at whether an exterior cladding recently installed during renovations on the West London residential building allowed the fire to leap to other floors.

The building became engulfed in flames in under an hour, trapping many people on the upper floors.

Aluminium composite panels are used to add insulation and to make a building more attractive, and consist of two metal panels sandwiching an inner material such as polyethylene, which was reportedly the case at Grenfell Tower.

The U.S. bans this type of cladding with a flammable plastic inner layer on buildings over 12 metres or roughly four storeys.

Costlier versions of the panels contain material that is more fire retardant.

Toronto Fire officials spoke out after the Grenfell Tower inferno to assure residents that protections in the Ontario Building Code and routine fire safety inspections will prevent a similar incident here.

Cripps said the Ontario Building Code applies to the construction of new buildings and renovations of existing structures.

“When an existing building is undergoing a renovation, upgraded fire safety measures may be required depending on the type of insulation and cladding proposed as part of the renovation,” he said.

aartuso@postmedia.com