Structural Post — What It Is, Uses, and Replacement

A structural post is a vertical load-bearing post made of wood, steel, or engineered lumber that supports beams and transfers loads downward.

Structural Post diagram — labeled parts, dimensions, and installation context

What It Is

Structural posts carry concentrated loads from beams, headers, roof framing, or decks into a footing or foundation below. They are different from decorative columns because they are part of the actual load path.

Post size, material, bracing, connections, and the footing underneath all affect whether the support is adequate.

Types

Common residential types include pressure-treated wood posts, solid-sawn posts, built-up posts, steel posts, and LVL or other engineered-lumber posts. Exterior posts may also be wrapped with trim, but the structural core still has to be sized correctly.

Where It Is Used

Structural posts are used in decks, porches, basements, crawl spaces, garages, additions, and large openings inside remodeled homes. They often support beams at ends, corners, or intermediate bearing points.

How to Identify One

Look for a vertical member directly under a beam or header that appears to be carrying weight. Structural posts usually line up with foundations or footings below, unlike purely decorative trim wraps or column covers.

Replacement

Replacement is a structural repair when a post is rotten, split, undersized, leaning, or resting on an inadequate base. Temporary shoring is usually needed so the load can be supported safely during the work.

Structural Post — FAQ

How is a structural post different from a decorative column?

A structural post carries building loads, while a decorative column may only hide or dress up another support. You cannot assume a decorative-looking column is nonstructural without checking.

What causes a deck post to rot at the bottom?

Constant wetting, poor drainage, and soil or concrete contact that traps moisture are common causes. Missing post bases and ground contact can shorten the life of wood posts.

Can a structural post be shortened or moved?

Only with a designed structural change. Altering a post changes the load path and can affect beams, footings, and the framing above.

Why is my support post cracking?

Wood posts often develop surface checks as they dry, which is not always a structural problem. Deep splitting, leaning, crushing, or movement at the beam connection deserves closer evaluation.