1. Determine if your roof only needs repaired or the entire roof should be replaced. You might receive different opinions from different roofers.
2. Ask the roofer how they will protect your windows, siding, shrubs, gutters, attic, lawn, etc. from damage. Find out how often they will remove the debris if they are taking off the old roof. Are they prepared for inclement weather? Will they put up temporary weather protection when they leave for the day?
3. If you are putting on a new roof, ask if removal of the old roof is necessary? Once again you may receive differing opinions, challenge the roofer to explain the difference of opinion.
4. Does the roofer need to replace only part of the existing sheathing or is all new sheathing required. If so, inquire about the type and thickness. You need to ask about the felt underlayment; what type and weight?
5. Make sure the roofer includes new flashing for the chimney, vent collar and valleys. What type will be used, will it be copper or aluminum and what gauge?
6. What shingles will be used (specific brand, grade, design, color)? Will the shingles be nailed or stapled?
7. Does the roofer guarantee his work? The guarantee should include the workmanship by the roofer and materials by the manufacturer. Since faulty application can invalidate the materials guarantee, sign a bid only if it has a workmanship guarantee.
8. Does the roofer have a certificate of insurance? Ask to see it. The contractor should have Workmen’s Compensation as well as liability.
9. Does the price include the permit and taxes? Does non-contracted work require your inspection and written approval? What is the payment schedule?
10. Request start and completion dates (including penalties); be sure this is made part of the contract.
11. Ask for references: Get the names, addresses, and phone numbers of four roofing jobs. They should be at least two or three years old (to see how the job held up). Call the references and ask them if they were satisfied with the work and if they had any problems. Ask them if they would hire this company again. Drive by and look at the jobs, do they look good, is the flashing neatly applied?
Ultimately when the bids are in you should choose a contractor on the basis of price, quality of work, reputation, and work completed on schedule and your general impressions of the company and its people.