A new study suggests that automation could eventually replace up to 49 percent of the country’s flesh-and-blood construction workforce by 2057 – that’s around 2.7 million people. However, carpenters who specialize in door and window installation might be safe – for a while.

The report, from the Midwest Economic Policy Institute (MEPI) and the Project for Middle Class Renewal at the University of Illinois at Urbana-Champaign, found that ten distinct skilled trades are at risk of being automated in the future.

“It is most likely a question of when— not if— blue-collar construction workers will face impacts from increasing automation of the construction industry,” said study co-author Robert Bruno. “To prevent the technological changes from inflicting economic damage on our once-thriving middle class, now is the time to promote policies that invest in the training programs that can prepare workers for the jobs of the future.”

The 49-percent reduction in the total construction workforce could nearly wipe out many jobs. For example, by 2057, the report says about 90 percent of operating engineers, cement masons and painters could be made redundant by robots.

Despite that, the report also notes that there are many tasks that currently can’t be automated, and that includes door and window installation.

Examples already exist of human door and window installers working alongside robots.

Blueprint Robotics in Baltimore builds modular housing on a robotic assembly line. The company says it can produce about 40 feet of framed wall in about 11 minutes. Robots then cut the rough openings for doors and windows. After drywall, insulation and siding are added, a pneumatic gantry lifts the doors or windows, sets them in the openings and secures them in place. Carpenters then finish the fastening and flashing.

“Whether through the use of robotics, virtual reality, or other technological innovations, automation has been increasing productivity, reducing costs, and improving quality,” said study co-author Jill Manzo. “With capital growing, the industry struggling with skilled labor shortages, and our nation facing growing infrastructure needs, it is fair to conclude that the pace of automation is likely to accelerate in the decades to come.”

Among the report’s recommendations is a bigger focus on education and training.

“Apprenticeship programs in the building trades should be utilized and adapted to train new workers and re-skill employees as specific trades become more automated,” the report reads. “States and local communities should collaborate with educational institutions to invest in vocational training and worker retrainingto prepare individuals for the jobs of the future.”

The construction industry has long struggled to embrace technological advances, and productivity has suffered because of it. According to a February report from the McKinsey Global Institute, productivity in manufacturing, retail and agriculture has grown by as much as 1,500 percent in the U.S. since 1945 thanks to advances such as automation, but it’s barely budged in construction. Globally, if construction productivity could catch up with the total economy, the industry’s value could rise by $1.6 trillion a year. That could meet half of the world’s infrastructure needs, according to the report.