Recoat suitability depends on the existing coating, adhesion, contamination, substrate, and proposed product. An old coating's presence is not proof that another layer will be compatible. Identification and assessment should precede selection.
What to do next
Ask how the contractor will determine the existing material and evaluate its condition. Request manufacturer-specific preparation and compatibility guidance. Where the old system cannot be identified, the proposal should explain that uncertainty rather than treating all coatings as interchangeable.
Related Perkins guidance
Contact Perkins Roofing to discuss your roof and the appropriate next step.