Sources and methodology.
Every material specification should be traceable. We prefer primary documentation and make uncertainty explicit instead of filling gaps with assumptions.
Source hierarchy
We generally prefer sources in this order, while recognizing that the best source can vary by field and product.
- Manufacturer manuals, engineering documents, installation guides, and official technical sheets.
- Official manufacturer product pages for the exact configuration.
- Authorized retailer pages when they provide configuration-specific commercial information such as current price.
- Other sources only when needed to identify a conflict or a gap, and not as a substitute for an available primary source.
Variant-level evidence
Specifications are attached to the exact variant whenever the evidence is variant-specific. We do not automatically copy a wind rating, snow load, weight, dimension, or installation claim from one size to every other size in the same family.
Unknown means unknown
If a reliable value is absent, it is stored and displayed as unknown or not verified. Non-positive placeholder dimensions and similar sentinel values are suppressed from publication. This prevents a missing field from looking like a measured zero.
Conflicts and manual review
When acceptable sources disagree on a material field, the affected record can be flagged for manual review. Variants with unresolved evidence problems are eligible to remain accessible for research, but are excluded from the SEO sitemap until the evidence is strong enough for intentional indexing.
Freshness
Product records include a last-verified date where available. Prices are observations, not guarantees, and can change after verification. We re-check source data as the catalog evolves and prioritize updates when a specification, merchant page, or product configuration changes.