Roof replacement cost by house size
A 1,500 square foot house needs about 18.8 squares of roof and costs around $10,450 to re-roof in architectural asphalt. Your roof is larger than your floor area, and the pitch decides by how much.
National average
$13,800
per project
On this page
- Work out your roof area first
- Cost by house size
- Why the price per square falls as the roof grows
- What the table does not include
- Frequently asked questions
- How do I measure my roof without climbing on it?
- Does a two-storey house cost more to roof than a single-storey?
- Is the garage included in these numbers?
- My quote is per square foot, not per square. Is that a red flag?
The first thing to know is that your roof is bigger than your house. Roofers price by the square, which is 100 square feet of roof surface, and roof surface is always larger than the floor area underneath it because the roof is tilted. A moderately pitched roof over a 2,000 square foot single-storey house covers about 2,500 square feet, or 25 squares.
That conversion is where most homeowners go wrong when they try to sanity-check a quote, so it is worth doing carefully before anything else.
Work out your roof area first
Start with the footprint, not the floor area. Those are the same number for a single-storey house. For a two-storey house they are not: a 2,000 square foot two-storey house sits on a 1,000 square foot footprint and has roughly half the roof of a 2,000 square foot ranch. This is the single biggest reason two houses of the same advertised size get quotes thousands of dollars apart.
Then multiply the footprint by a pitch factor:
- Nearly flat, up to 3/12: multiply by 1.05
- Low slope, 4/12 to 5/12: multiply by 1.12
- Standard, 6/12 to 8/12: multiply by 1.25
- Steep, 9/12 and above: multiply by 1.42
Divide the result by 100 and you have your number of squares. Most suburban houses built after 1970 have a standard pitch, so 1.25 is the right guess if you do not know.
Cost by house size
Architectural asphalt shingle, standard pitch, single storey, with one existing layer stripped off. These are national figures before any regional adjustment.
| House footprint | Roof squares | Low | Typical | High |
|---|---|---|---|---|
| 1,000 sq ft | 12.5 | $5,100 | $7,100 | $10,250 |
| 1,200 sq ft | 15.0 | $6,050 | $8,450 | $12,150 |
| 1,500 sq ft | 18.8 | $7,500 | $10,450 | $14,950 |
| 1,800 sq ft | 22.5 | $8,950 | $12,450 | $17,750 |
| 2,000 sq ft | 25.0 | $9,900 | $13,800 | $19,600 |
| 2,500 sq ft | 31.3 | $12,300 | $17,150 | $24,300 |
| 3,000 sq ft | 37.5 | $14,700 | $20,500 | $29,000 |
The low column is a simple roof, a competitive local market and a contractor who is not busy. The high column is a cut-up roof with several valleys and dormers, a steep pitch, or a market where roofers are booked out after a storm.
Why the price per square falls as the roof grows
A 3,000 square foot house does not cost three times what a 1,000 square foot house costs, even though the table above looks close to linear. Setup, tear-off staging, the dumpster, the permit and the crew's travel are largely fixed. Spread over 12 squares they are noticeable; spread over 38 they nearly disappear.
The effect is real but modest, usually 5% to 10% per square between the smallest and largest jobs. It is not a reason to replace more roof than you need.
What the table does not include
Anything the crew finds after the old shingles come off. Rotten deck sheathing runs $70 to $150 per 4x8 sheet installed, and it is the most common reason a final invoice exceeds the estimate. A second layer of old shingles to remove adds roughly $85 to $200 per square. New ridge venting, chimney flashing and skylight curbs are separate lines.
Ask for the per-sheet decking rate in writing before work starts. A contractor who will not name it before the roof is open is asking you to sign a blank cheque.
Frequently asked questions
How do I measure my roof without climbing on it?
Measure the footprint of the house at ground level with a tape or from a plot plan, then apply the pitch factor above. For an irregular house, break it into rectangles and add them up. This gets you within about 10% of a professional measurement, which is close enough to check a quote against.
Does a two-storey house cost more to roof than a single-storey?
Per square it does, by roughly 15%, because the crew needs more staging and material handling takes longer. In total it usually costs less, because a two-storey house of the same floor area has half the roof.
Is the garage included in these numbers?
No. An attached garage is roof area like any other. A standard two-car garage adds roughly 4 to 6 squares, or $2,100 to $3,200 at typical rates.
My quote is per square foot, not per square. Is that a red flag?
Not on its own, but check the arithmetic. A quote of $5.50 per square foot is $550 per square. If the number looks suspiciously low, confirm whether it covers the roof area or the floor area, because those differ by 25% on a standard pitch.
Read next
Asphalt shingle roof cost$386 to $749per squareAn asphalt shingle roof costs $386 to $749 per square installed, so a 20 square roof is $8,200 to $15,400. The material is the smaller half of that; labour and tear-off are the rest.
Roof replacement cost by state$9,300 to $13,650per projectThe same 20 square asphalt roof costs about $9,300 in Arkansas and $13,650 in Alaska. The gap is almost entirely what an hour of skilled labour costs in each state.
Metal roof cost$11,000 to $60,000per projectA standing seam metal roof runs about $27,000 on a typical house, roughly two and a half times an asphalt roof. Most of the premium is labour, not material.
Roof decking replacement cost$150 to $400per eachReplacing roof decking costs $150 to $400 per 4x8 sheet. It is the line that most often makes a final invoice beat the estimate, and nobody can quote it honestly in advance.
How to pay for a roof$386 to $749per squareA roof is usually a $14,000 bill arriving without notice. How it is paid changes the total by thousands, and contractor 0% offers are often deferred interest rather than free money.