How We Calculate Roof Costs
Most roofing cost pages give you a number and no way to check it. This page is the check.
Below is every source behind the figures on this site, how often each one updates, and — the part nobody else publishes — what we have not verified yet.
The Short Version
- Price movement comes from federal Producer Price Index data. It is public, monthly, and you can pull it yourself.
- Product specifications come from published manufacturer literature.
- Product prices are currently editorial estimates. They are labelled as estimates everywhere they appear, and replacing them with independently sourced figures is our open work.
- Regional cost ranges are modelled, not surveyed. We say so on the page they appear on.
- We never ask for your email to show you a number.
Where the Numbers Come From
Federal price index data (public domain, monthly)
Our cost index tracks four Producer Price Index series published by the U.S. Bureau of Labor Statistics. BLS data is public domain and free to republish with citation.
| Series | What it measures | June 2026 | Year over year |
|---|---|---|---|
PCU3241223241222 | Prepared asphalt roofing products — the closest available proxy for shingles | 375.52 | +2.2% |
WPU1361 | Asphalt roofing and siding products | 367.585 | +2.2% |
PCU324122324122 | Asphalt shingle and coating manufacturing | 369.692 | +2.7% |
PCU23816X23816X | Roofing contractor services | 228.649 | +5.5% |
A limitation we will not paper over: the contractor services index covers nonresidential roofing. BLS publishes no residential roofing labor series. We use it because it is the best available signal for labor direction, not because it is a perfect match for your house.
Pulled from the BLS public API on 2026-07-25 and refreshed monthly. BLS publishes mid-month for the prior month, and figures stay preliminary for four months, so recent months revise slightly.
Manufacturer specifications
Wind ratings, impact ratings, algae warranty terms, and shingle weights come from published manufacturer product literature and the underlying test standards (ASTM D3161 and ASTM D7158). These are verifiable: every figure we publish can be checked against the manufacturer's own documentation.
Product pricing — currently unverified
This is the honest part. Per-product prices on this site are editorial estimates, last reviewed March 2026. They are not drawn from a named external source.
4 of 4 product price entries carry this status:
- GAF Timberline HDZ — estimate, last reviewed March 2026
- CertainTeed Landmark — estimate, last reviewed March 2026
- CertainTeed Landmark PRO — estimate, last reviewed March 2026
- Owens Corning TruDefinition Duration — estimate, last reviewed March 2026
Why they are not sourced yet: distributor pricing (ABC Supply, Beacon, SRS) is account-negotiated and not public. Retail shelf pricing covers only part of the market. We would rather label an estimate as an estimate than dress it up with a citation that does not support it.
What we are doing about it: moving these onto observed retail pricing and published cost data, indexed forward with the BLS series above. Until then, treat them as a starting range, not a quote.
Regional cost ranges
Carolinas market ranges are modelled: a regional baseline adjusted for local labor rates, permit costs, and wind-zone requirements. They are not survey results, and we do not present them as per-city precision they do not have. That is why the market table groups by region rather than publishing a falsely exact figure for every town.
How the Estimate Math Works
When we price a roof, this is the arithmetic. No black box.
- Roof area. Footprint area × a pitch factor × roughly 10% for overhang. The pitch factor is √(1 + (rise/12)²) — 1.118 at 6/12, 1.202 at 8/12, 1.302 at 10/12.
- Squares. Roof area divided by 100. One square = 100 sq ft.
- Waste. 7–10% on a simple gable, 10–12% with a valley or two, about 15% on a hip, 20–25% on a complex roof with dormers.
- Tear-off. $100–$175 per square for one layer, plus $50–$100 per square for each additional layer. Building code requires full tear-off at two existing layers.
- Steep-pitch labor. Walkable to 6/12. Add 15–25% at 7–9/12, and 30–70% at 10/12 and above. Two-storey adds 10–15%.
- Allowances. Decking replacement is shown as a range, not a fixed number, because nobody knows until the old roof is off. Penetrations, flashing, and trim carry a flat allowance.
What this math cannot do: it cannot see your ridge, hip, and valley linear footage. No aerial data source below contractor-grade measurement reports provides it. We fold that into the waste factor and the trim allowance rather than pretending to a precision we do not have.
How Accurate Is This?
Expect any estimate here to land within roughly 15–20% of a real quote for a straightforward roof, and wider on a complex one.
The things that move a real quote outside that band are the things no calculator can see from a distance: decking condition under the old shingles, how many layers are actually up there, chimney and skylight flashing detail, and whether your roof has the kind of geometry that slows a crew down.
An estimate here is a starting point, not a quote. Only an on-site inspection can price your actual roof.
Update Cadence
| Data | Updates | Last updated |
|---|---|---|
| BLS price index series | Monthly, automated | 2026-07-25 |
| Product specifications | On manufacturer revision | March 2026 |
| Product pricing | Quarterly target | March 2026 |
| Regional cost model | Quarterly target | March 2026 |
Any page on this site that stamps a year in its title is checked against these dates when the site is built. If the data behind it has gone stale, the build fails rather than shipping a page that claims to be current and is not.
What We Do Not Do
- We do not gate numbers behind a form. No email, no phone number, no zip code required to see a price.
- We do not publish user ratings we do not have. No invented star ratings on product pages.
- We do not grade named contractors. If we assess a quote, we assess the number against a range — not the company that wrote it.
- We do not present modelled figures as surveyed ones.
Corrections
If a figure here is wrong, we want to know. Pricing varies more by market and by job than any single range can capture, and a real quote that falls well outside our band is useful information about our model, not an embarrassment.
See the pricing changelog for what has changed and when.
Sources
- U.S. Bureau of Labor Statistics, Producer Price Index. bls.gov/ppi. Public domain; see BLS copyright information. Retrieved 2026-07-25.
- ASTM D3161 and ASTM D7158, wind resistance test standards for asphalt shingles.
- Manufacturer product literature: GAF, CertainTeed, Owens Corning. Specifications only.
- International Residential Code, section R908.3, on re-covering versus full tear-off.