In ASR A2.1 , “fall-through resistant” is the term used to describe roof areas and components that do not break when you walk over them so that there is no danger of falling.
Here is a list of roof components that are typically non-fall-through resistant:
It should not be generally possible to access a roof surface which is not fall-through resistant. Access may only be granted to individuals who have been specially trained. In addition, you must install a clearly visible sign at the access point to the area in question stating that only those access routes may be used that are clearly marked. You might decide to use catwalks to mark these access routes.
Such catwalks must be capable of withstanding the expected loads resulting from individuals walking over them and transporting work equipment; they must be at least 0.5 m wide and have a guard rail on both sides. If guard rails on both sides would impede the work that needs to be carried out, a single guard rail on one side, combined with suitable anchorage devices, would also be a possible solution.
If a domed rooflight or light panel was not designed to be fall-through resistant, a guard rail must be set up around it. Whilst work is being carried out, you must either cover it up or stretch a protective layer across underneath it. This also applies to access routes that pass through a fall danger zone in the vicinity of a domed rooflight or light panel. One of the places where you can find information on the specific requirements pertaining to non-fall–through resistant components is in the DIN 4426 standard.
After having carried out your risk assessment, you might decide to secure all the access routes and workplaces located in or near a non-fall-through resistant roof area with appropriate anchorage devices - combined with suitable PPE equipment.