What to ask before you sign anything

"What does your workmanship warranty cover, and for how long?"

Ask for it in writing, in the company name, with a term. Five to ten years is common; the term matters less than whether they will still be trading.

"Can I see a job you finished five years ago?"

Recent work shows tidiness. Older work shows competence. Ask for the older one.

"What happens if the decking is rotten?"

The right answer is a specific price per sheet, written into the contract before work starts. A vague answer here is how a fixed price stops being fixed on day two.

"Who is actually doing the work?"

Ask how long this specific crew has worked together. Roofing companies keep their name and change their hands more often than most trades.

"What underlayment, and how are the valleys done?"

This is the question that reveals whether you are comparing the same roof. Underlayment, ice-and-water placement, drip edge and valley treatment are where quotes quietly diverge.

"What is your licence number, and who holds it?"

The follow-up matters more than the answer: does the entity on the licence match the entity on the paperwork, and is it active today?

In short

Six questions, three contractors, one afternoon. It is the cheapest insurance available on a job this size.