The homeowner would only be liable if at fault in some way--for example, the homeowner had some unsafe condition on the property (e.g. a staircase with a rotten step or railing that broke when the worker put weight on it which they failed to fix and which caused the accident) or the homeowner him/herself caused the injury (like by bumping into a ladder, knocking a worker off it). The homeowner is not liable simply because he/she hired the contractor or it is his/her property.The contractor employing the worker would similarly be liable if at fault (e.g. gave out unsafe equipment or tools, didn't provide basic safety equipment or training, had the workers do something inherently unsafe). If there is no one but the worker or just pure chance at fault (e.g. the worker didn't look were he was going and fell, or refused to clip on a safety line he'd been given; a tree limb happened to fall on a worker when he was walking past), then no one else is liable.