Technically, no. But while the subcontractors workers are not your employees, you’d still be legally responsible for their safety–at least to the extent that the work takes place on your premises and under your control. So, you really do need to provide them the training and acquaint them with the hazards of the property.
One more thing: Since roofing is a form of “construction” work, you could delegate primary responsibility for OHS compliance and safety for the project by making the subcontractor (or another contractor who’s in charge of the work) the “constructor.” But that’s a pretty big deal and requires a lawyer’s help.
Hope that helps. Glenn
