Piles foundations are typically found in coastal areas and are used when there is a layer of weak soil at the surface. Supports are driven into the ground and embedded several feet below grade.
Post and pier construction uses a series of posts installed under the home which are mounted to concrete piers. Sometimes cladding or facing is added to cover the space below the elevated house. This type of foundation is common in coastal pre-FIRM structures. Post-FIRM, or structures built after the effective FIRM was adopted by the community, must be built with more resilient, NFIP-compliant foundations.