How a roof price is built
Roofs are priced by the square — 100 square feet of roof surface. Your roof is bigger than your floor plan because of slope and overhangs, so the calculator estimates it from your home size, stories, garage, and steepness. Then the price per square depends on what’s on and under your roof.
What moves the number
- Size and steepness. More squares, and steep roofs take longer and need more safety gear.
- Complexity. Valleys, dormers, and multiple levels add labor and material.
- Layers. More than one old layer means more tear-off and disposal.
- Decking. Rotted wood under the shingles gets replaced — only visible once the old roof is off.
- Flashing and vents. Chimneys, skylights, walls, and pipes need new flashing; poor attic ventilation may need fixing.
- Material. Architectural shingles are the standard; designer shingles and metal cost more.
What your itemized price will list
Tear-off and disposal, decking (and how replacement wood is priced), underlayment and leak barrier, flashing, ventilation, the shingle line and color, ridge and edge parts, and cleanup. Compare quotes line by line — the lowest number isn’t the lowest cost if it leaves something out.