Roof Replacement Cost Calculator

What actually drives the price

Roof size is the obvious one, and it is measured in squares — one square is 100 square feet of roof surface. The number that matters is the area of the roof itself, not the floor area of the house. A single-story home with a moderate pitch has roughly 10 to 30% more roof than footprint, so a 1,800 square foot house usually has somewhere around 21 squares of roof.

Cost per square falls as a roof gets larger, because disposal, the permit and getting a crew on site cost much the same whether the roof is small or big. A very small roof is rarely cheap in proportion to its size.

After size, three things move a quote more than most people expect.

Pitch

Up to about 6/12, a roofer can walk the roof and work at normal speed. Past that they need staging, harnesses and more time, and the quote climbs 25 to 50% for the same area. A steep roof is not slightly harder; it is a different job.

Story count

Every bundle has to get up there, and every piece of the old roof has to come down. Two stories typically adds 10 to 15%, and three or more can add close to 30%.

What is under the shingles

This is the one that turns a predictable job into an unpredictable one. Decking is only visible once the old roof is off, and soft or rotten sheathing has to be replaced before anything else goes on. Most quotes include a per-sheet price for replacement decking rather than a fixed allowance, because nobody knows how many sheets are bad until the tear-off.

What a quote should itemize

A quote that is one number and a signature line is not enough information to compare against anything. A reasonable one separates at least these:

• Tear-off and disposal. How many layers are coming off, and whether a dumpster is included. Two layers is roughly double the removal labor of one.
• Decking replacement. A per-sheet rate, so you know what a surprise costs before you are standing in it.
• Underlayment. Synthetic is standard now. Ice-and-water shield along the eaves is required by code in cold climates and worth having regardless.
• Shingles. Brand, line and color. "Architectural shingles" covers a wide price range.
• Flashing. Whether chimney, valley and wall flashing is being replaced or reused. Reusing old flashing is where a cheap quote often gets cheap, and it is also where roofs leak.
• Ventilation. Ridge vent, soffit intake, or neither. Poor ventilation shortens shingle life considerably.
• Permit. Whether it is included or billed on.
• Warranty. The manufacturer covers the shingles; the roofer covers the work. Those are different lengths and the workmanship one matters more.

Shingle types compared

Architectural shingles cost around a quarter more than three-tab and last roughly half again as long, which is why they have become the standard. On a 21 square roof the whole difference is about $570 of material for five to ten more years of roof, and that is before the wind rating, which is 110 to 130 mph against three-tab's 60 to 70. The step up to designer shingles is a much larger jump for a much smaller gain in life, and is mostly an appearance decision.

How to compare quotes

Three quotes that look similar can describe quite different jobs. Work through them in this order:

1. Check the roof area each one used. If the square counts differ by more than a square or two, somebody measured wrong, and everything downstream of that is wrong too.
2. Confirm tear-off versus roof-over. These are not the same job and should never be compared on price alone.
3. Find the decking rate. It should be a per-sheet price, not an allowance. An allowance means you find out what it really cost after the work is done.
4. Compare flashing line by line. Replaced or reused, and at the chimney, valleys and walls specifically.
5. Read both warranties. The manufacturer covers the shingles. The roofer covers the work. The second one is the one that matters, and the one that varies.
6. Ask who is actually on the roof. Employed crew or subcontracted, and whether the person quoting will be there.

Labor against materials

Materials account for about 57% of the direct cost of an asphalt roof replacement in this model, labor for about 34%, and fixed items such as disposal and the permit for the remaining 9%. The common rule of thumb puts labor nearer 60%, and the gap is worth explaining rather than hiding.

Two things pull in opposite directions here. Material prices on this page come from retail shelf prices, and a roofing contractor buys at distributor rates that typically run 20 to 30% below them, so the material share is overstated. Labor is priced at the published trade wage plus a burden for taxes and insurance, which is a real cost but excludes the contractor's margin — that sits in the separate overhead line rather than inside labor. Measured the way a contractor talks about a job, labor and materials land much closer to even.

The ratio matters for one practical reason. Two roofers using the same shingle on the same house should land close on materials, so a large gap between quotes is almost always in the labor line. That means fewer people, less time, a crew that will not come back, or something quietly left out of the scope.

Flashing and ventilation

Flashing

Flashing causes more leaks than shingles do. Water enters a roof at its interruptions — the chimney, the valleys, the walls a roof meets, the vent penetrations — and flashing is what seals them. Replacing it adds a few hundred dollars to a quote and is the single cheapest piece of insurance on the job. Reusing old flashing is the most common reason a new roof leaks in its first winter.

Ventilation

Ventilation decides how long the roof lasts. A roof needs intake at the soffits and exhaust at the ridge, and the two have to be balanced; ridge vent alone with blocked soffits moves almost no air. Inadequate ventilation can cut a third off the life of a shingle rated for thirty years, which makes it the most expensive corner anyone cuts on a roof.

Permits, warranties and insurance

Permits

A re-roof needs a permit almost everywhere, and the fee is small relative to the job. Skipping it saves a little and surfaces later, because an unpermitted roof shows up in the inspection when the house is sold.

Warranties

Two warranties come with a new roof and they are not the same thing. The manufacturer warrants the shingles against defect, which is rarely what goes wrong. The roofer warrants the workmanship, which is what actually fails, and that warranty is only worth the lifespan of the business behind it.

Insurance

Insurance pays for sudden damage such as hail or wind, not for a roof that has worn out. The distinction that catches people is how the payout is calculated. A replacement cost value policy pays what a new roof costs. An actual cash value policy deducts depreciation first, so a twenty-year-old roof may be settled at a fraction of the replacement price with the homeowner covering the rest. Many policies quietly move older roofs onto actual cash value at renewal.

When the cheap quote is cheap for a bad reason

Some gaps are legitimate. A roofer with a slow month genuinely prices lower than one booked into next season. But a quote well below the others usually involves at least one of:

• Roofing over the existing layer rather than tearing off. It is faster and cheaper, it is legal in many places up to two layers, and it hides whatever is wrong with the decking while shortening the life of the new roof.
• Reusing flashing. Saves a few hundred dollars and is the most common place a new roof leaks.
• No permit. Fine until you sell the house and it shows up in the inspection.
• No workmanship warranty, or one from a business too new to honor it.
• A large deposit. Materials are usually delivered on credit. A roofer asking for half up front before anything arrives is managing their cash flow with your money.

Timing

Roofing is seasonal and the price follows demand. Late spring through early fall is peak and quotes run highest. Late fall and winter are cheaper where weather allows the work at all, though asphalt shingles need a reasonable temperature to seal properly.

The exception is after a storm. When a hailstorm goes through a region, every roofer within an hour is booked and out-of-state crews arrive. Prices rise, quality becomes a lottery, and the pressure to sign quickly is deliberate. If your roof is not actively leaking, waiting out that window is usually the better call.

How long it takes

Most single-family asphalt roofs are a one to three day job for a full crew. The sequence is fixed, and knowing it tells you whether a schedule you are being quoted is realistic:

1. Tear-off. The old roof comes off, usually in a morning.
2. Decking inspection and repair. Soft sheets are found and replaced here, which is the only point at which the real condition of the roof is known.
3. Dry-in. Underlayment and ice-and-water shield go on the same day as the tear-off, because a roof cannot be left open overnight.
4. Shingles, flashing and ventilation. The bulk of the visible work.
5. Cleanup and magnet sweep. Nails end up in the lawn and the driveway, and a crew that skips this leaves you finding them with a tire.

If a roofer tells you tear-off is day one and shingles start on day three, ask what happens if it rains on day two.