Best Practice Guidelines for Working on Roofs
The guidelines provide practical guidance to employers, contractors, employees, designers, principals, persons who control a place of work, and architects who are engaged in work associated with roofing. The guidelines apply to a wide range of work situations where workers are placed in a position from which falls are possible. These situations include new roof installations, re-roofing, repairs and maintenance work on roofs.
Importance is placed on managing the hazards associated with working on roofs by identifying hazards through planning, assessing, and controlling the hazards. This includes planning safe access to the roof, inspecting the roof for potential height hazards, and identifying and assessing brittle roofing.
Source : http://www.osh.dol.govt.nz/order/catalogue/pdf/roofs-best-practice.pdf