Methodology: How This Library Is Written
Every page on this site is built the same way: facts traced to primary sources — federal regulations, HUD guidance, ICC-ES evaluation reports, and manufacturer installation documents — written in plain language, reviewed by a licensed Professional Engineer, and dated. Where a fact can’t be traced, we say so rather than guessing.
Where the facts come from
Claims about what codes require come from the codes: 24 CFR Parts 3280, 3282, and 3285; HUD’s Permanent Foundations Guide for Manufactured Housing (HUD-4930.3G); FHA handbook language; ICC-ES evaluation reports such as ESR-4725; and manufacturer installation manuals, cited by document name and revision. Secondary sources (industry publications, cost surveys) appear only for facts that have no primary source — market cost ranges, for example — and are labeled as such. The full list lives on the sources page. Manufacturer documents are summarized and cited, never republished.
Precision over reach
The most damaging errors in this topic come from blurring categories, so we hold a hard line: the PFGMH governs HUD-code manufactured homes only, and pages about modular or Boxabl-class units may reference its criteria by analogy, never as the governing standard. Product certifications are described at their actual scope — a panel report is not a unit rating — and a seismic design category is a property of a site, not of a product. Where the honest answer is “it depends on your jurisdiction,” the page says that instead of inventing a national rule.
Engineer review, with dates
Every article is written or reviewed by Enrique Lairet, PE, and carries a reviewed-by date. Pages are re-checked on a quarterly cadence, and sooner when a cited source changes — evaluation reports get reissued, manufacturer lineups change, and regulations get amended. If a page shows a reviewed date, it means someone actually checked it against the sources on that date.
What we won’t promise
Nothing on this site promises what an engineer’s letter would disclaim. We do not “guarantee compliance” or offer “assurance” that a foundation will pass review — the most an honest engineer can say is that they can confirm compliance where the evidence supports it, so that is how we write. Educational content here is not site-specific engineering; final determinations always rest with the authority having jurisdiction and a licensed engineer looking at the actual site and structure.
Respect for the audience
These are real homes and real homeowners. A $50,000 home deserves the same serious engineering process as a $500,000 one, and readers deserve content free of stigma, scare tactics, and manufactured urgency. Where an inexpensive option is the right answer, we say so.
Corrections
When we find an error — or a reader does — we correct the page and update its reviewed date. Corrections that change a substantive fact are noted on the page. Found something? Tell us.