What is the typical lifespan of a pier and beam foundation?
There is no fixed number, and that is the honest answer rather than a dodge. Plenty of pier and beam houses in Dallas are a century old and structurally sound. What has a lifespan is the wood: beams, joists and shims fail when moisture gets to them, and all of it is replaceable without touching the rest of the house. That repairability is the genuine advantage this construction has over a slab.
Moisture is what kills a crawl space, not age
A dry crawl space with air moving through it can carry a house indefinitely. A wet one rots shims, softens beam ends and invites everything that eats wood, and it does that in years rather than decades.
Water gets in from the obvious places: grading that slopes toward the house, a downspout emptying beside the skirting, blocked vents, or a plumbing leak under the floor. Almost every pier and beam repair traces back to one of those.
What actually gets replaced
Individual piers can be reset or replaced where they have settled. Rotten shims come out and new ones go in. A beam end that has taken on water gets sistered or replaced across that span. None of it requires disturbing the house above in the way slab work does.
That is why a pier and beam house that has been maintained does not have an expiry date. It has a maintenance history.
How it is fixed, in order
Somebody goes under the house and looks properly, rather than glancing in from the access hatch. Readings establish where the floor has dropped and by how much. New concrete piers go under the points that have lost support, and the floor comes back up in stages so the finishes above are not shocked.
Then the moisture problem gets dealt with, because setting new supports into a crawl space that is still taking on water buys you the same repair again in a few years.
Related questions
Is pier and beam worse than slab?
Neither is worse. Pier and beam is more repairable and gives you access to plumbing. Slab needs less maintenance but is harder and costlier to correct once it has moved.
Should I add a vapor barrier?
In a crawl space with damp ground it usually helps, because most of the moisture is evaporating up out of the soil. It is worth asking about while somebody is already under there.
How often should a crawl space be inspected?
Every few years is reasonable, and sooner if you notice a floor starting to slope or a musty smell in the rooms above.
