There are many risks associated with working at height ranging from the access and egress to a roof to roof obstacles such as plant and roof lights. The illustration below gives a clearer example.
When designing a system for our clients we would always as a first resort opt for a fall restraint system. This where the system is set back typically 2.3m from any roof hazard or fall with the operative utlising a 1.8m lanyard. This enables the operative to reach the area of work, i.e. the gutter or downpipe without being able to reach the fall or danger zone. The short video clips below demonstrate the difference between fall arrest and fall restraint.