What’s in these numbers

Each total is a typical one-story house with a plain gable roof, measured the way the roofing calculator measures it: 12 inch overhangs, a 6/12 pitch and 10% shingle waste. Priced the way a contractor’s estimate is priced:

  • Architectural (laminated) shingles with felt, the old roof torn off. The guide to 3-tab vs architectural shingles prices the same roofs in 3-tab.
  • Drip edge on the eaves and rakes, starter strip, and ridge cap along the ridge.
  • Three pipe jack flashings, for the plumbing vents most houses have.
  • Overhead and profit: 20%, the standard markup on a contractor’s estimate.
  • Sales tax on the materials, at the state’s average rate.

Not in them: replacing rotten decking, ice and water barrier (required in cold climates), roof vents, step and chimney flashing, a second layer to tear off, and permits. The metal roof cost guide prices the same houses in steel panels, and the roof repair cost guide prices fixes short of a new roof.

What moves the price

  • Size and pitch. The roof is bigger than the house: overhangs and slope add to it, and a steeper roof is slower and needs more safety gear. A 12/12 roof has 41% more area than its footprint.
  • The shape. Hips, valleys and dormers mean more cutting, more waste and more flashing than a plain gable.
  • Two stories. The roof over a two-story house of the same floor area is about half the size, but harder to reach.
  • The decking. Soft or rotten sheathing is replaced by the sheet once the old roof is off.
  • Layers. A roof can’t be covered over when it already has two layers (IRC R908.3.1.1), and each layer adds to the tear-off.
  • Climate. Where ice dams form, the code calls for an ice barrier from the eave to at least 24 inches inside the wall line (IRC R905.1.2).
  • Where you live. Pick your state in the box above.

Working out your own roof

  1. Measure the house and the overhang, and find the pitch. The guide to measuring a roof covers three ways.
  2. Run the roofing calculator for the squares, bundles and edges.
  3. Type the house’s footprint in the box above for the range by footprint, or compare the house sizes in the table. The roof cost estimator puts shingles, steel and flat roofs side by side for your house.

Common questions

How much does a new roof cost on a 1,500 square foot house?

For a one-story house with a plain gable roof, about $9,700 to $14,700, by the footprint figure above. A hip roof, a steep pitch or a second layer to tear off raises it.

How much is a roof replacement on a 2,500 square foot house?

A one-story house of that size comes to about $15,700 to $23,250, typically $18,700. On a two-story house of 2,500 square feet the roof is about half the size.

How many bundles of shingles for a roof?

Most architectural and 3-tab shingles come three bundles to a square of 100 square feet (GAF). The roofing calculator counts them with waste.

Will insurance pay for a new roof?

When a covered event such as hail or wind damages it, a homeowner’s policy usually pays to repair or replace the damaged roof, less the deductible and subject to the policy’s terms. The adjuster’s estimate itemizes the work; contractors often ask for items it missed. The roof replacement coverage guide covers when a policy pays and how much.

Can new shingles go over the old ones?

Sometimes, once. The code doesn’t allow a new roof over one that already has two layers (IRC R908.3.1.1), or over a roof that is wet or damaged.