Is it legal to lock the roof door of the property?

It is legal, but it must be approved by government departments, abide by government decisions, and pay attention to the protection of personal privacy. The National Emergency Plan for Public Health Emergencies stipulates that:

(eight) to carry out mass prevention and treatment: streets, townships (towns), neighborhood committees and village committees shall assist health administrative departments and other medical institutions to collect and report epidemic information, evacuate and isolate people, and implement public health measures. According to the above regulations, the community has the right to take measures to close the community to ensure the safety of residents' access.