In three short years, the design/build firm Katerra has grown from a Silicon Valley entrepreneur’s bright idea into what soon could be one of the largest commercial residential construction firms in the country. The strategy: vertically integrate every layer of construction, from design to the fixtures and subcontracting in order to lower costs, build faster, and raise quality. The means: venture capital (over $1 billion so far) plus acquisitions of existing companies in the building and products industry. Now Katerra is moving to buy architecture firms, and today is announcing the acquisition of the mass timber innovator Michael Green Architecture of Vancouver, with a staff of 25. … “It was love at first sight,” said Michael Marks, chairman and co-founder of Katerra, by phone. …To date, Katerra has focused on market-rate multi-family housing… But the company is plotting a major mass timber push with a state-of-the-art 250,000-square-foot CLT factory in Spokane, Washington, opening in early 2019.