How much does a new roof cost?

Roofers price per square. One square is 100 square feet of roof surface. It is not a square foot, not a square yard, and not a sheet of plywood, and it is the single most common source of confusion when a homeowner reads a proposal.

Two conversions have to happen before a price means anything.

First, your house's footprint is not your roof's area. A pitched roof is the hypotenuse over the plan area, so you multiply by a pitch factor: 1.031 at 4/12, 1.083 at 5/12, 1.118 at 6/12, 1.202 at 8/12, 1.302 at 10/12, 1.414 at 12/12. A 2,000 sq ft footprint at 6/12 is 2,236 sq ft of roof, plus the overhangs.

Second, that area becomes squares by dividing by 100. So 2,236 sq ft is 22.4 squares, and you order 23.

When a quote says "$525 a square", it means $5.25 a square foot of roof. When a quote says $14,000 with no squares on it, you cannot check the price against anything, and you should ask for the square count. Any roofer who won't give you one has not measured.

On a straightforward asphalt re-roof, the rough split looks like this:

• Shingles: $110–$180 per square in material for architectural, $75–$110 for three-tab, $250–$450 for designer laminates
• Underlayment: $15–$45 per square, synthetic; ice-and-water membrane at eaves and valleys is $50–$90 per square of the area it covers
• Starter and ridge cap: $60–$120 per square of ridge and eave length, not of field area
• Drip edge: $2–$4 per linear foot installed
• Flashing: $10–$25 per linear foot for step and counter flashing, and a chimney reflash is commonly $400–$1,000 on its own
• Labor: $150–$350 per square, which is the largest single line and the one that varies most by market and by pitch
• Tear-off and disposal: $100–$175 per square per layer
• Permit: $150–$500 depending on jurisdiction

Deck repair is not in there, because it cannot be known until the old roof is off. What you want in the contract is a per-sheet price for replacement sheathing — commonly $70 to $130 per 4x8 sheet installed — rather than a vague allowance. A roof needing four sheets is normal. A roof needing twenty is a different conversation you should be having on the day, with photographs.

Tear-off runs about $1.00 to $1.75 per square foot, so $100 to $175 a square, doubled if there are already two layers. On a 23-square roof that is $2,300 to $4,000 before the second layer.

Going over the top saves that money and costs you three things: you never see the deck, the new shingles run hotter and age faster, and the finished roof telegraphs every imperfection underneath. Manufacturers will still warrant material over one existing layer, but the wind ratings assume proper fastener penetration into the deck, and nails through two layers of shingle hold worse.

I would tear off on any house I planned to keep for more than five years. The exception I'd genuinely make: a rental or a property under contract, one existing layer, sound deck, and a buyer who has already been told. That is a legitimate use of a legitimate technique, not a shortcut.

Disposal is priced by weight, and asphalt is heavy — a square of removed architectural shingles is roughly 250 to 400 lbs. A 20-yard dumpster at $400 to $700 typically covers a 25-square single-layer tear-off. Two layers usually means two hauls.

Two roofs of the same square count can differ by 60% in price, and the reason is almost never the shingle.

Pitch. Anything to about 6/12 is walkable and a crew moves fast. From 7/12 they slow down, from 9/12 they need roof jacks and staging, and past 12/12 you are paying for fall protection setup and a crew that will do half the squares a day. Expect a 20% adder over 7/12 and 40–60% over 10/12.

Cut-up roofs. Every valley, hip, dormer, skylight and chimney is hand work — cutting, weaving, flashing — while the open field is production work. A simple gable might go down at three squares an hour; a valley takes as long per foot as several squares of field. Waste climbs too: 10% on a plain gable, 15–18% on a hip roof with dormers, because every cut piece leaves an offcut.

Height and access. A second storey adds staging, longer ladder throws and slower material handling. A third storey or a house you cannot get a dump trailer beside adds real hours.

Penetrations. A roof with twelve plumbing vents, three bath fans, a chimney, two skylights and a solar array is a flashing job with some shingling attached. Solar panel removal and reinstall for a re-roof commonly runs $1,500 to $4,000 and is quoted by the solar company, not the roofer.

This is why "how much per square foot" is answerable and "how much for my roof" needs a measurement. Get the square count and the number of valleys, and the range narrows fast.

Installed, all-in, per square foot:

• Three-tab asphalt: $3.50–$5.50
• Architectural asphalt: $4.50–$8.00
• Exposed-fastener metal panel: $6.00–$12.00
• Standing-seam metal: $10.00–$18.00
• Concrete tile: $10.00–$20.00, plus a structural check because it weighs 6–11 lbs/sq ft
• Clay tile: $12.00–$25.00
• Natural slate: $20.00–$40.00, and it needs a slater rather than a roofer
• TPO or EPDM on a flat roof: $5.50–$12.00

Three-tab is a false economy on anything but a rental you plan to sell. The material saving is around $50 to $70 a square — perhaps $1,500 on a whole roof — and you give up a third of the roof's life and a wind rating of 60 mph against 110 or 130. The labor, tear-off, flashing and disposal cost the same either way, so you are saving 8% of the job to lose 30% of the service life.

Tile and slate carry a structural question that asphalt does not. Asphalt is about 2.5 lbs per square foot; concrete tile is three to four times that. A framing structure built for shingles may need reinforcement, and that is an engineer's letter and a permit, not a roofer's judgment call.

Insist on four numbers on every bid: square count, number of layers being removed, the specific shingle product and colour, and the per-sheet price for deck replacement. With those four, three bids become genuinely comparable. Without them you are comparing three lump sums that describe different jobs.

Then check the parts that separate a good roof from a cheap one. Is the underlayment synthetic or 15 lb felt? Is there ice-and-water membrane at the eaves, and how far up — code in cold climates is typically to a point 24 inches inside the interior wall line. Is the flashing new, or is it being reused and caulked? Is the ventilation being corrected, or just reinstalled as found? Are there starter strips at eaves *and* rakes?

A quote that is 25% below the others is usually short on exactly those lines. Ask which one it is missing before assuming the roofer is just hungrier.

Payment structure tells you something too. A deposit of 10–30% for material is normal. A demand for half up front is not, and payment in full before the final inspection never is.