Methodology
Where the numbers come from
In order of preference:
- Building codes and government sources (International Residential Code, U.S. Department of Energy, FEMA, state agencies).
- Independent evaluation and rating bodies (ICC Evaluation Service, Cool Roof Rating Council, ASTM and UL standards as cited by those bodies).
- Manufacturer documents: warranties, data sheets, installation instructions and code evaluation reports.
- Peer-reviewed research.
We do not use forum posts, contractor blogs or AI-generated summaries as sources.
How each page is checked
- Every row in a comparison table links to its source.
- Each page shows the date its sources were last checked.
- When a source does not say something, we say so instead of filling the gap.
- Prices are shown only when a citable source publishes them, with that source's date. Otherwise the page has no price.
- We compare documents, not installed roofs. Real performance also depends on installation, climate and maintenance.
Updates and corrections
Manufacturers change warranties and products. We recheck sources at least once a year and whenever we learn of a change. Corrections are dated on the page. Report an error to [email protected].