What questions should I ask a roofing contractor before hiring?

Licensing and insurance are non negotiable. Ask for a current contractor license number and verify it with your state. Ask for proof of general liability and workers compensation insurance. If a contractor is injured on your property and uninsured, you're potentially liable.
Years in business matters. A contractor with 10 plus years in the same area has reputation to protect. New contractors sometimes undercut on price but disappear before warranty claims arise. Ask for references and actually call three of them. Ask previous customers about communication, cleanup, and whether the job took the estimated time.
Job scope clarity
Does the quote include removal of the old roof, or will they layer over it? Layering is faster and cheaper but hides underlying damage. Removal takes longer but lets roofers inspect the decking and spot rot. Ask about debris disposal; are dump fees included in the quote? Get timeline in writing, not just a promise.
Warranty and dispute resolution
What's covered and for how long? Material warranties come from manufacturers; workmanship warranties come from the contractor. A solid contractor stands behind their work for at least a few years. Ask how disputes are handled if something goes wrong after payment. A written contract protects both of you.