A roof attachment system has a stud for retaining a fixture to a roof and is mountable to and sealable with a roof. The attachment system includes a base and a retaining stud which projects upwardly from the base. A membrane is disposed over the base. Cooperative upper and lower mount plates include peripheral oppositely projecting teeth which form an intermediate axial gap. A retainer ring is disposed in into the gap and alternately engages against the teeth of the upper and lower mount plates to axially tighten the attachment components to provide a seal.