What are safety roles during installation of skylight on fragile roof?

proper PPE(helmet, gasses/face shield, gloves), falling arrestor/harnesses belt, man basket, barricaded zone and signs,PTW- cold work, toolbox talk 

QRA with a detailed MS to assess the best practices is where you should start off with, of cause with the whole team involved with proper brainstorm meetup.

A competent Supervisor for the activity, Competent HSE Adviser, Competent Lifting Supervisor.

The Safety department is to check all the requirements given in the approved method statement, requirement of lifting activity, plants to be used as per load assessment, training certificates of all the operators involved, certification of all the equipment to be used, working at height requirements, PTW for all high risk activities, for any electrical works required for installation, Emergency preparedness. All to be as per approved QRA.

proper method statement which identify the sequence of work and the steps should be followed as required, well maintained of risk assessment should be in place identifying all the hazards and the control measures.

the main risk is falling of personnel / objects from height and through the skylight open holes, slip and trip over the roof sheets, all the previous will require a proper planning for the emergency response in case god forbid accident occurs, proper fall prevention system need to be in place (proper barriers , full body harness used by a qualified and trained user), proper signage in place (work at height, falling objects, unauthorized access), safety mesh.