Roof Replacement Cost
Cost per square, what tear-off adds, and where quotes hide things.
Compiled by DIY Repair Guide · reviewed 2026-09-05 ·how we research these
Roofing is quoted in <strong>squares</strong>. One square is 100 square feet of roof surface. A typical single-storey house has 15 to 25 squares, and knowing that alone makes quotes far easier to compare, because it turns a lump sum into a rate you can check.
The material choice sets the range, but the things that move a quote within that range are tear-off, pitch, access, and whatever is found under the old shingles.
Cost by Material
Installed, including tear-off of one existing layer, underlayment, standard flashing and disposal.
- Architectural shingle is the default on most US replacements. A modest premium over 3-tab for meaningfully longer life and better wind rating.
- Metal costs roughly double asphalt and lasts roughly double. On a house you intend to keep, the arithmetic works. On one you will sell in five years, it does not.
- Tile and slate carry a weight problem. Both are far heavier than asphalt, and a structure framed for shingles may need reinforcing before either can go on.
| Material | Per square | Typical 20-square roof | Life |
|---|---|---|---|
| 3-tab asphalt shingle | $350–550 | $7,000–11,000 | 15–20 yrs |
| Architectural asphalt shingle | $450–750 | $9,000–15,000 | 25–30 yrs |
| Wood shake | $800–1,400 | $16,000–28,000 | 25–40 yrs |
| Standing seam metal | $900–1,600 | $18,000–32,000 | 40–70 yrs |
| Corrugated metal panel | $500–900 | $10,000–18,000 | 30–45 yrs |
| Clay or concrete tile | $1,000–2,000 | $20,000–40,000 | 50+ yrs |
| Slate | $1,500–3,000 | $30,000–60,000 | 75–150 yrs |
| Flat roof, thermoplastic polyolefin (TPO) or synthetic rubber (EPDM) | $450–900 | $9,000–18,000 | 20–30 yrs |
Working Out Your Roof Size
Roof area is not floor area. A roof is a sloped surface, so it is always larger than the footprint beneath it, and steeper roofs are larger still.
A rough method: take the building footprint in square feet and multiply by a pitch factor. A gentle 4/12 pitch is about 1.05, a common 6/12 is about 1.12, a steep 12/12 is about 1.41. Then add for overhangs, dormers and any complexity. Divide by 100 for squares.
A 1,800 square foot single-storey house with a 6/12 roof is roughly 2,000 square feet of roof, or 20 squares, which is why the 20-square column above is the useful one for most homes.
Ask every roofer for the square count in their quote. If three quotes disagree on how many squares your roof is, at least one of them has not measured it, and that is the quote most likely to grow once work starts.
What Tear-off Adds, and Why Layering Is a False Economy
Removing the existing roof typically adds $100 to $200 per square, covering labor and disposal. Most codes allow at most two layers of asphalt shingle, so a roof already carrying two must be stripped.
Roofing over an existing layer saves that money and is legal in many places with one existing layer. It is still usually a poor idea. Nobody inspects the deck for rot, the new shingles telegraph the irregularities of the old ones, the assembly runs hotter which shortens shingle life, and the next replacement is more expensive because two layers have to come off.
The one thing a tear-off buys you that nothing else can is a look at the deck.
The Unknown That Changes the Price
Nobody can see the roof deck until the old covering is off, so almost every roofing contract carries a per-sheet rate for replacing rotten plywood. This is normal and not a scam. But the rate should be agreed in writing beforehand.
Typical figures run $70 to $150 per sheet of plywood installed. On a roof that has been leaking quietly for years, twenty sheets is not unusual, and that is a $2,000 surprise if you did not know the rate.
| Item | Typical additional cost |
|---|---|
| Deck replacement | $70–150 per 4x8 sheet |
| Second layer tear-off | $100–200 per square |
| New drip edge | $2–5 per linear ft |
| Ice and water shield | $1.50–3 per sq ft of coverage |
| Ridge vent | $300–800 |
| Chimney flashing rebuild | $300–1,200 |
| Skylight reflash | $300–800 each |
| Skylight replacement | $900–2,500 each |
| Gutter replacement | $1,200–3,500 |
| Permit | $150–500 |
What a Cheap Quote Is Usually Leaving Out
The spread between the low and high quote is rarely profit margin. It is usually scope.
- Underlayment quality. Synthetic underlayment outperforms felt and costs more. A quote that does not say which is using the cheaper one.
- Ice and water shield. In cold climates this is required at eaves and valleys, and it is a common omission.
- New flashing. Reusing old flashing around chimneys, walls and valleys is the single most common corner cut, and flashing is where most roofs actually leak.
- Drip edge. Required by code in most places and frequently missing from budget quotes.
- Ventilation. A roof without adequate intake and exhaust ventilation cooks its own shingles and can void the warranty.
- Disposal and cleanup. Including a magnet sweep for nails, which matters more than it sounds if you have tyres or bare feet.
- The warranty split. Manufacturer warranties cover material. Workmanship warranties come from the roofer and range from one year to lifetime. Most leaks are workmanship.
Be wary of storm-chaser crews that appear after hail. Check that the contractor is licensed and insured in your state, has a physical local address, and will still exist when the workmanship warranty matters. Ask for a certificate of insurance directly from the insurer rather than a photocopy.
When It Actually Needs Replacing
Age is the strongest signal. An asphalt roof past twenty years is near the end regardless of how it looks from the ground. Beyond that, the reliable indicators are visible from a ladder or from inside.
- Curling, cupping or clawing shingles across large areas rather than in one spot.
- Granules in the gutters. Some shedding is normal on a new roof. Heavy accumulation on an old one means the shingles are failing.
- Bald patches where the asphalt substrate is visible.
- Daylight through the roof deck seen from the attic, or damp sheathing and staining.
- Sagging along a ridge or between rafters, which is structural rather than cosmetic and needs an engineer instead of a roofer.
- Repeated leaks in different places. One leak is a repair. Three are a roof.
Common questions
How much does it cost to replace a roof?
For a typical 20-square asphalt roof, $9,000 to $15,000 installed with architectural shingles, or $7,000 to $11,000 with basic 3-tab. Metal, tile and slate run from roughly double to several times that.
What is a square in roofing?
100 square feet of roof surface. Roofers price in squares, so asking for the square count in a quote lets you compare three bids as a rate rather than as three lump sums.
Can I put a new roof over the old one?
Often legal with one existing layer, but usually unwise. Nobody inspects the deck for rot, the new shingles telegraph the old surface, the assembly runs hotter and wears faster, and the eventual tear-off costs more.
How much does it cost to replace rotten roof decking?
Commonly $70 to $150 per sheet installed. Nobody can see the deck until the old roof is off, so agree the per-sheet rate in writing before work starts rather than discovering it mid-job.
How long does a roof replacement take?
An average asphalt roof is typically one to three days. Complex roofs, tile, slate and metal take longer, and weather delays are normal since most of the work cannot happen in rain.