There was a deep dive about this in Bloomberg Odd Lots podcast. Although some of the price increase was due to the industry predicting lower demand and getting

There was a deep dive about this in Bloomberg Odd Lots podcast. Although some of the price increase was due to the industry predicting lower demand and getting rid of inventory. Another, more fundamental factor is the actual scarcity of lumber due to lower harvesting quotas set by Canadian govt. These quotas are unlikely to go up any time soon.