What are helical anchors or piles, and when are they used?

Helical anchors are steel shafts with screw-shaped plates that are turned into the ground; they resist pulling and are the usual way to tie a manufactured-style home down. Delaware's natural resources agency lists helical earth anchors, concrete anchors and cross-drive anchors as the main types, and FEMA describes auger-type, screw-in ground anchors strapped to the frame. Larger engineered piles, whether driven or screwed in, can also carry the home's weight and raise it in flood or coastal areas, which FEMA covers in its guidance on pile foundations. In rock or caliche where augers will not turn in, Texas rules allow cross-drive rock anchors with adjusted spacing. Pile foundations are engineered, so expect a design and permit.

Check your local rule. This varies by state, county or city. Your permitting office has the final word; the official lookup pages below show you who that is.

Sources

• Adaptation Strategy: Anchor Manufactured HomeDelaware Department of Natural Resources and Environmental Control
• FEMA P-85, Protecting Manufactured Homes from Floods and Other HazardsFEMA
• 10 Tex. Admin. Code 80.24, Generic Standards for Anchoring SystemsLegal Information Institute, Cornell Law School (Texas regulation text)