Understand what an overlay leaves concealed
A new shingle layer does not reveal the entire deck or the details beneath the existing roof. Ask how the contractor evaluated known leaks, uneven surfaces and possible deterioration, and what could remain unknown if the covering stays.
GAF permits certain reroof applications under stated conditions and also identifies conditions that call for removal. Permission for a product in general does not establish eligibility for a specific house.
Understand what tear-off allows
Removal gives the contractor access to inspect the deck and address deficient areas before rebuilding the covering. GAF also notes that certain enhanced warranties require a complete tear-off. Ask for the exact proposed warranty and installation instructions rather than assuming all warranties treat overlays alike.
Discuss how deck findings will be priced and authorized. The proposal should explain the work included in the base price and how additional quantities will be documented.
Resolve the project-specific requirements
Have the contractor confirm the existing roof layers, acceptable substrate, required details and applicable jurisdictional rules. Do not apply a code statement from another city or an older manufacturer bulletin as a current local determination.
- What roof materials and layers are already present?
- Is the existing surface suitable for the proposed installation?
- How will flashing and roof-edge details be handled?
- How will deck concerns be investigated?
- Does the specified warranty allow this exact approach?
Compare the work, not only the first invoice
Ask both proposals to state demolition, disposal, deck evaluation, flashing and installation scope. An overlay option should explain its limitations; a tear-off option should explain how newly exposed conditions are managed. Either decision should be tied to verified conditions and current project requirements.