Home › Sources & Method
Sources & Method
Every number on this site traces to a published standard. Here is the list, and how each page is checked.
Every source this site cites
236 documents are cited across 138 calculators. This list is generated from the pages themselves at every build, so it cannot disagree with what they actually cite.
The pattern worth noticing is how few of them are the building code. Roughly half this site rests on manufacturers' own installation instructions, trade-body product manuals and consensus standards, because that is where the answer actually lives for composite decking, chain link, vinyl fencing, trusses, stain coverage and structural panels. Where the code does govern, the page names the section and prints the table.
How values are verified
A figure does not go on a page until it has been read from the code text or the standard itself. Secondary sources (other calculator sites, summaries, aggregators)are not treated as sources, because they have repeatedly been found wrong. Two of the best-ranking deck calculators on the web currently disagree with IRC Table R507.5(1) and with each other.
Two specific traps are worth naming, because they caught us:
- State documents are not the base code. A Pennsylvania stair guide reproduces IRC R311.7 accurately except for the riser and tread dimensions, which Pennsylvania amends: exactly the values a reader would come for.
- Code databases silently substitute jurisdictions. A query for residential guard requirements returned Illinois commercial code. Any source used here has to state which code, which edition and which jurisdiction it is showing.
The build check
Every figure quoted in a worked example is declared as an assertion and executed against the same data the calculator uses, each time the site is rebuilt. If a table is edited and the paragraph beneath it no longer matches, the build fails and the page does not publish. The visible table and the calculator's own lookup are generated from a single source, so the two cannot drift apart.
Editions and amendments
Values here are drawn from the 2018 and 2021 IRC unless a page says otherwise. Adoption is state and county specific, and local amendments are common: some jurisdictions rewrite stair dimensions outright. Confirm against the edition your building department enforces.