A 12-storey building proposed for Portland's Pearl District has received the go-ahead from planners, paving the way for it to become the USA's first high-rise wooden structure.

The Framework Building, designed by Lever Architecture to be built from mass timber, was approved for construction by the State of Oregon and the City of Portland this week.

Buildings with load-bearing wooden structures over 85 feet (30 metres) tall were previously not permitted by US codes.

Therefore the proposed timber frame, which includes a combination of engineered woods like cross-laminated timber (CLT) and glue-laminated timber (Glulam), had to undergo rigorous testing to meet seismic, fire and acoustic requirements.

The material is becoming an increasingly popular choice for architects, who claim that wood is taking over from steel and concrete as the architectural wonder material of the 21st century.

"Receiving a permit is a critical juncture for Framework and demonstrates the feasibility of using wood to build high-rise buildings in the US," said project developer Anyeley Hallova.

"With our path now clear to start building, Framework will start to unlock the demand for mass timber products at all scales justifying new investment into rural manufacturing and job creation."

The mixed-use tower will include retail space on the ground floor, five storeys of offices, and another five of studio, one- and two-bedroom apartments totalling 60 homes.

Rooftop amenities and parking for 102 bikes also feature in the proposal for the site at 430 Northwest 10th Avenue.

The project was first unveiled in December 2015. Construction is set to commence later this year, with completion due for winter 2018, when it is predicted to become the tallest all-mass-timber building in North America.

"The innovations in wood construction that are part of the design of the Framework building will help change how America builds in the years to come," said Steve Lovett, CEO of the Softwood Lumber Board organisation that contributed to the research and development work on the project.

Elsewhere on the continent, new details of Shigeru Ban's plans for the "world's tallest hybrid timber structure" in Vancouver were revealed last week.

A seven-storey mass-timber building was completed in Minneapolis at the end of 2016, however SHoP Architect's proposal for New York's tallest timber tower was axed in March 2017.