Research methodology
Our source hierarchy, model matching, unknown-data rules and calculator verification approach.
Source hierarchy
Exact-model manufacturer pages, manuals and specification sheets are the primary source for product details. Extension publications support general technical methods. Retailer or affiliate-network descriptions can identify a lead, but do not silently override manufacturer data. A source-check date records when we reviewed the source, not when a product was tested.
Identity before numbers
We record the model, size selection and generation where available. A dimension from one revision is not automatically assigned to another. Original units and manufacturer terminology remain visible. Converted or calculated figures must be identifiable as our arithmetic rather than a new manufacturer claim.
Unknown means unknown
A blank verified field means we have not established the answer from the reviewed evidence. It does not mean zero, none or unsuitable. Conflicting data is flagged and withheld from normalized measurements when assigning an axis would be guesswork. We do not rank unlike wind or snow claims as though their test conditions were equivalent.
Tools and quality checks
Calculators display inputs, formulas, unit conventions and limits. Automated checks cover numerical examples, invalid inputs and browser behavior. A software check confirms the implementation of the stated model; it does not certify the model for an individual structure or installation.
Changes and corrections
We update a record when reliable evidence changes the answer. Material conflicts should remain explained until resolved with a source. Contact us with the page URL, exact model or revision and supporting documentation. We do not require a commercial relationship to consider a correction.