You don't need a permit for roof replacement in Phoenix. Phoenix law requires that anyone doing work on the exterior of any building must have a valid permitting or licensing and inspection process finished by either the City of Phoenix Department's Contract Plumbing section, Building Services Section, Air Quality Section, Business Vitality Section, Electrical Division Environmental Compliance Division or Fire Prevention Bureau. However, there are some exemptions to this rule: if the replacement is a result of an act of nature (e.g., a storm), then no permit is needed; if the roofing material is the same as what was previously on the roof, then no permit is needed; or if the work will not disturb the roof deck, then no permit is needed. If you are not sure whether your project requires a permit, it is always best to check with the City of Phoenix. You can do this by calling their Permit Inquiry Line at 602-262-7111 or visiting their website. For more information on permits and licensing in Phoenix, please visit the following website: https://www.phoenix.gov/buildings/permits-licenses-inspections