On the night of March 20, the state of California's Governor Gavin Newsom's office issued a full list of Essential Critical Infrastructure Workers on their COVID-19 resource page. The update clearly outlines construction as an essential service during the COVID-19 outbreak.
The exemption, found at the top of page 11, reads:

"Construction Workers who support the construction, operation, inspection, and maintenance of construction sites and construction projects (including housing construction)."