How can a homeowner make sure a roofing contractor pays the subcontractors so that there is no lien placed on the home?

This is very simple. All you need to do is make all checks for payment to the roofing contractor payable to BOTH the roofing contractor as well as any subcontractors or suppliers working on your home. That way, the subcontractors are paid. Another, more complicated method is to have all subcontractors sign lien releases. Lien release forms are available in "Do-it-yourself" forms packages in office supply stores or online. A more accurate, state specific form can be obtained from a real estate attorney in your area.