I want to use an aerial lift to clean my windows. Why do I need to install rooftop equipment?

You may not need to install permanent rooftop equipment. Depending upon building height, features of the building, aspects of the perimeter of the building, obstructions for accessing the exterior, the strengths of the structure and surrounding structures, climatic conditions, etc, alternative solutions may be available. However, consideration should still be given to evaluating all conditions of your building to determine if there are any safety hazards with the desired means of access.

In California however, it is a requirement to install tie-back anchors at a minimum. Title 8, Article 6, Section 3291(f)