24 CFR § 3285.308
Manufactured piers
February 22, 2021
(a) Manufactured piers must be listed and labeled and installed to the pier manufacturer's installation instructions. See §3285.303(d)(2) for additional requirements.
(b) Metal or other manufactured piers must be provided with protection against weather deterioration and corrosion at least equivalent to that provided by a coating of zinc on steel of .30 oz./ft.2 of surface coated.