A review of Governor Baker's list of COVID-19 Essential Services, issued March 23, 2020, shows construction is considered an essential service and exempt from the closing of workplaces.
Those portions applicable to MCA members:
"Construction Workers who support the construction, operation, inspection, and maintenance of construction sites and construction projects (including housing construction)" - page 8
"Workers – including contracted vendors – involved in the construction of critical or strategic infrastructure including public works construction, airport operations, water, sewer, gas, electrical, nuclear, oil refining and other critical energy services, roads and highways, public transportation, solid waste collection and removal, and internet, and telecommunications systems (including the provision of essential global, national, and local infrastructure for computing services)" - page 6
"Workers such as plumbers, electricians, exterminators, inspectors and other service providers who provide services that are necessary to maintaining the safety, sanitation, and essential operation of residences, construction sites and projects, and needed facilities" - page 6