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Headings are set in Source Serif 4. Frank Grießhammer drew it for Adobe, and it is free to use under the SIL Open Font License. Tables, figure labels, margin notes and anything holding data are set in IBM Plex Sans Condensed, from IBM's Plex family, also SIL OFL. The body text is your own device's font. It loads at once, and it reads the way your machine always reads. We cut both web fonts down to the Latin letters and serve them from this site. Nothing is pulled from a font network.

Every number here traces back to a named source with a date. Bureau of Labor Statistics wage surveys. Climate zone files from PNNL and the Department of Energy. Census Bureau maps. A maker's own coverage chart. The building codes as the ICC publishes them. Each input is tagged measured, derived or estimated. An estimate is labeled as one every time it appears. A number we have not pinned down never gets published at all. The full method is on the methodology page. The data itself is on the data pages, free to quote if you credit us.

The charts and maps are drawn by code, straight from the same data files the text cites. So a chart cannot disagree with the sentence next to it. The climate zone map and the state code map are drawn from U.S. Census Bureau boundary files. Those are federal work, so nobody owns them. They are colored from the same federal data the rest of the site runs on. Every chart and map names its sources under the frame, because a chart is a claim.

If an image has a credit under it, that image is a real photograph, and the credit is its license. Either federal work that nobody owns, or Creative Commons with the photographer named. Every other image on this site was made with an image model. That is the rule. We state it once, here, instead of under every picture. Three lines about how we make images would be three lines that are not about your attic.

There is one line we do not cross. Some pictures are things you hold your own attic up against. Vermiculite and asbestos. Mold. Rat and mouse mess. Those are real photographs or nothing at all. A made-up picture of a hazard could send somebody to the wrong call about their own house. Our illustrations show how a thing is laid out or done. They are never evidence. And no picture here shows a job as ours, because none of them is.

The site is built with Astro and served as flat pages from a content delivery network. No page carries a tracking script, an analytics pixel or an ad network. A page can call out to exactly one outside service: the spam check on the quote form. It only loads if you go near the form.

Before any change goes live, twenty-seven checks run against the built site. Any one of them can stop it. They catch an em dash. A British spelling. A cost table with no method. An answer block that runs too long or too short. A page claiming a license nobody holds. A schema type this site does not use. An affiliate link with no disclosure. A paragraph printed twice in a row. A number that no longer matches the data file it came from. Most of these checks were written the day something slipped through without one.

Some errors get past the checks anyway. Those get fixed on the page and written up, with a date, in the corrections list. Ours go there too. Write to [email protected] with the number, the page, and the source that says otherwise.