How a roof replacement job goes
Most roof replacements follow the same order. The crew protects your landscaping and covers the ground. They tear off the old shingles down to the wood deck. They inspect the exposed decking for soft or rotted spots. Then they lay new underlayment, flashing, and drip edge. Finally they install your chosen material and clean the site.
A typical home takes one to three days. A simple, single-story roof can finish in a day. A large, steep, or complex roof takes longer. Weather can pause the work, because crews will not install on a wet deck. A dumpster sits in the driveway for the tear-off debris.
Good crews stage the job carefully. They never leave your deck open to rain overnight. They dry-in the roof with underlayment before they stop each day. Ask your contractor how they plan the days and protect the interior. A clear plan is a sign of an organized company. Use the calculator above to size your own job first.
What really moves your price
Roof size drives the biggest share of the cost. Roofers measure in squares, and one square covers 100 square feet. A typical house roof runs about 20 to 25 squares. More squares mean more material and more labor. Your footprint and roof shape set this number, not your floor area.
Material choice is the next big factor. Three-tab asphalt is the cheapest option. Architectural asphalt costs more but lasts longer. Metal, tile, and cedar shake cost several times more per square than basic asphalt. Heavier materials also need a stronger deck and sometimes extra framing.
Labor climbs with tear-off layers, pitch, and access. Removing two old layers costs more than removing one. A steep roof forces crews to use ropes and move slowly. Hard access, tall walls, and many valleys add hours. Rotted decking is a common surprise. Crews replace bad plywood before they install, and that adds cost.
Permits, codes, and warranties
Most cities require a permit for a roof replacement. The permit protects you, because it triggers an inspection. Codes often limit how many shingle layers a roof may carry. Many codes cap the total at two layers. If you already have two, a full tear-off is required by law.
Codes also set rules for underlayment, flashing, and ventilation. Ice-and-water shield is required in cold climates along eaves. Proper attic ventilation protects the deck and the shingles. A contractor who pulls the permit follows these rules. One who skips the permit may skip the details too.
Two warranties come with a new roof. The manufacturer warranty covers the material itself. The workmanship warranty covers the installation labor. These are separate promises from separate parties. Read both, and learn how long each lasts. Some manufacturers offer a stronger warranty only through certified installers. Ask whether your bid includes that upgraded coverage.
How to hire and vet a roofer
Start with license and insurance. Confirm the contractor holds the license your state or city requires. Ask for proof of liability insurance and workers compensation. Call the insurer to confirm the policy is active. This step protects you if a worker is hurt on your property.
Get itemized bids from at least three contractors. A good bid lists tear-off, underlayment, flashing, material, and cleanup as separate lines. It names the exact product and color. It states the number of layers to remove. Vague, one-line bids hide the real scope and invite change orders.
Check manufacturer certification and local reputation. Some manufacturers train and approve installers, and that unlocks better warranties. Ask for recent local references and drive by finished jobs. Read reviews with an eye for how the company handles problems. The lowest number is not always the best value. Compare scope, not just price.
Red flags and avoiding overpaying
Be careful with storm chasers. These crews follow hail and wind into a town. They knock on doors and push you to sign fast. Many leave the state before any warranty matters. A local company with a fixed address is a safer choice. It will still be here if the roof leaks.
Watch for insurance games. Some crews offer to waive or absorb your deductible. That practice is illegal in many states and can void your claim. A contractor who inflates the scope to your insurer puts you at risk. Keep your own copy of the claim and the estimate.
Protect yourself on scope and payment. Reject vague per-square bids that do not name the material. Never let a crew skip underlayment or flashing to lower the number. Those hidden layers keep water out for decades. Avoid large deposits, and never pay in full before the work starts. Tie payments to real milestones.