A contractor working on your property could sue you if he is injured while on your property. This point is especially true if you failed to take precautions or warn the worker of any obvious risks. The best ways to protect yourself against a damaging lawsuit are to check your home insurance policy, and to require that a contractor carry his own insurance.
Your homeowner's policy includes standard liability coverage. Some people add an umbrella policy to increase benefits. This insurance pays medical costs and legal defense costs when you get hit with a liability claim. It is important to review your policy terms and talk with your agent, though, as the types of events covered and amount of benefits paid on a standard home policy vary.
USLegal strongly advises people to require contractors to have their own insurance prior to starting on the project. Reputable contractors buy insurance to cover their own risks of injury, as well as liability resulting when they damage your property. This insurance mitigates some of your risk. When a crew comes, check to see that the employer has workers' compensation benefits. Otherwise, you could face a lawsuit from a worker or subcontractor.