A Montreal construction company is building a 10-storey condo building from the top down.

The unusual method is being tested on the Rubic construction site on René-Lévesque Blvd. at Amherst St.

The process saw builders first assemble a first floor and a roof. The roof was then lifted and each floor then sandwiched below the roof.

No scaffolding or crane is required and the construction site does not spill into the street.

Upbrella Construction President Joël Larouche, who says he thought up the process, believes the construction to be a world-first.

"This approach is the future for small lots where there is no place to work," he said.

Construction workers also appreciate being sheltered from bad weather. "The roof offers protection from rain and snow, so you don't waste time," said site supervisor Sylvain Gauthier.

Another advantage is that the method allows developers to adjust the height of their project during construction.

"When the economic market is so-so, banks will invest because we can start with a 40-floor project and when the market drops off, you can stop at the 20th and sell or rent it out," said Rubic Construction President Luc Poirier.

The building is expected to be completed by July 1st, 2016.