A post-and-pier foundation supports a structure using vertical wood or steel posts resting on concrete piers, raising the floor framing above grade on a grid of individual support points. It’s a traditional foundation style still common under older homes and in areas where a raised, ventilated crawl space is preferred.
The posts themselves are often adjustable or replaceable, which historically made this foundation type popular in regions without heavy earthmoving equipment.
What Does a Post-and-Pier Foundation Involve?
- Concrete piers set into the ground at regular intervals
- Wood or steel posts resting on each pier
- Beams spanning between posts to support floor joists
- An open, ventilated space beneath the structure
Why Are Post-and-Pier Foundations Important?
This foundation style allows a home to sit above grade with minimal excavation, which made it popular before modern equipment made basement excavation more affordable, and it remains useful on sloped or hard-to-excavate sites. Because the posts and connections are accessible, this type of foundation is also relatively easy to inspect and repair compared to a foundation buried entirely underground, though the wood posts themselves are vulnerable to rot and pest damage if moisture isn’t controlled.
Homeowners with an older post-and-pier foundation often find that individual posts can be leveled or replaced one at a time as needed, without the extensive excavation a comparable repair to a basement foundation wall would require. Because the space beneath the home stays open and ventilated, this foundation type also tends to keep floor systems drier and less prone to the moisture-related issues sometimes seen in sealed crawl spaces.
Post-and-Pier Foundation vs. Pier Foundation
A pier foundation may support a structure directly on piers alone, while a post-and-pier foundation specifically adds a post between the pier and the framing above, often allowing for a taller crawl space or easier adjustment over time as the structure settles.