A lining may be an option for a sound gutter substrate, but it is not a universal repair. Capacity, falls, outlets, joints, corrosion, movement and the condition of adjacent roof interfaces should be assessed first.
Evidence for procurement
Ask for dimensions, drainage observations, preparation requirements, product compatibility, details at outlets and expansion points, access controls and a written description of guarantee coverage. A condition survey should explain whether cleaning, local repair, lining or replacement is proposed and why.
Safety and ownership
Gutter work is roof work: access, falls and fragile surfaces must be controlled. See commercial gutter lining for an owner-led discussion.