Do manufactured homes in Iowa and Minnesota need tie-downs, and how do I know mine are right?

Yes, and anchoring is the part of a manufactured home most likely to be missing, corroded or loosened over time — which is why it gets close attention on every one of these inspections. Under HUD's Basic Wind Zone Map at 24 CFR 3280.305, all of Iowa and all of Minnesota are in Wind Zone I, the standard wind zone. Wind Zones II and III are assigned to hurricane-exposed coastal counties and island territories, which the regulation lists by name, and no Iowa or Minnesota county appears on either list. It is worth being clear about what that does and does not mean: the wind zone system is built around hurricane exposure, and a Wind Zone I rating does not mean a home is designed to survive a tornado or a derecho. For Wind Zone I homes, 24 CFR 3280.306(a) requires the support and anchoring system to resist the standard design wind loads increased by a factor of 1.5 — a safety margin on the anchoring, which is precisely why the condition of that anchoring is worth verifying in a region with the straight-line wind and derecho history this one has. The installation standards at 24 CFR Part 3285, Subpart E give us concrete things to check. Ground anchors must be installed to their full depth, with stabilizer plates where the anchor's listing or certification requires them, following the anchor and home manufacturer instructions. Straps must be placed within two feet of the ends of the home, and the diagonal strap angle to the ground must be between 30 and 60 degrees. Anchors must be certified by a professional engineer or architect, or listed by a nationally recognized testing laboratory. Anchors must also be embedded below the frost line unless the foundation system is frost-protected under 24 CFR 3285.312(b) and 3285.404 — and for manufactured homes in Iowa, state rule defines a frost-protected footing as foundation material installed to a depth of 42 inches below finished grade and requires ground anchors to reach below that 42-inch frost depth. The defects we find are concrete: severed, slack, rusted or missing straps; anchors pulled partway out of the ground or never driven to full depth; strap angles outside the 30-to-60-degree range; anchoring installed on one side only; and homes strapped to nothing more substantial than a concrete block.