The short answer
A construction-site security officer follows written post orders built around the jobsite’s actual risks. Typical duties include checking gates and perimeter fencing, verifying authorized employees and vendors, logging visitors and deliveries, patrolling material-storage areas, observing equipment and fuel locations, and documenting unusual activity. During off-hours, the officer may check doors, trailers, lighting, locks, and previously identified vulnerable areas on a defined patrol schedule.
What to know
Good construction security is primarily preventive and observational. The officer maintains a visible presence, identifies conditions that need attention, preserves relevant observations, and reports incidents through the agreed chain of command. If an emergency occurs, the officer follows site procedures, contacts 911 or the designated responder when appropriate, protects the scene from unnecessary disturbance, and records facts without speculating. The officer should not perform construction work, replace a competent safety person, or enter hazardous areas outside the assignment and training.
Before coverage begins, the contractor and security provider should document access rules, emergency contacts, delivery procedures, restricted areas, required personal protective equipment, and reporting expectations. That site-specific briefing is what turns a generic patrol into an accountable security function.