When to Repair or Replace a Rusted Support Pole in Basement

Marwa Hasan
Written by Marwa Hasan
Reviewed by Andy Kilborn
Updated January 31, 2022
An open-plan kitchen in the basement of a house
Photo: PhotoSerg / Adobe Stock


  • Replacing a steel support beam costs around $3,100.

  • If you spot rust in your basement support posts, call a general contractor.

  • Rusty support columns can be repaired or replaced.

  • Prevent rust from appearing on basement poles by treating them.

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Steel posts in the basement help support the floor above. But these important structural elements are susceptible to rust if they are located in a damp area or not regularly maintained. If you notice signs of rust in your crawl space or basement poles during a renovation or regular check-up, it's time to consider repairing or replacing your posts before they fail and affect the structural integrity of your home.

"Degraded support poles should be replaced or repaired quickly before worse damage occurs,” says Andy Kilborn, Expert Review Board Member and Owner of Andy’s Handyman Service.

Signs of a Rusted Support Pole in the Basement

If your house is old, you will need to watch for failure signs in steel and Lally posts in your basement. An expert inspection is usually the way to go since they can find key indicators, but as a homeowner, you can regularly evaluate the condition of a steel support column with clues like visible rust.

Visible Rust

  • If there is heavy flaking, deep corrosion, or holing throughout

  • If you see rust at any part of the metal support pole

  • If you see signs of the pole crumpling, or bending, or out of alignment

Structural Clues

  • Any signs of movement 

  • A dip in the ground

  • Cracks, bends, or bowing in floors, walls, and ceilings

  • A sudden collapse of the upstairs floor 

Test the Post

Scrape the column with a screwdriver to see the rust flakes. It will only require cosmetic repair if rust is light and superficial, though it might be an early warning sign. If the rust is deep and has compromised the structural integrity of the column, then this indicates a necessary column replacement.

You can also tap the post with a hummer or a screwdriver at mid-span. Notice the sound. A ringing sound is good if the noise is followed with more of a thunk because the post is probably concrete-filled and unlikely to crush. However, a dull ding means it has a very thin metal, indicating a deteriorating hollow post.

Why Do Basement Support Poles Rust?

Rust in the crawl space or basement poles is usually due to excessive humidity. Sometimes rust is an indicator of a problem that you can't see. But other times, it's an obvious reason, such as basement flooding due to rain or water seepage from improper drainage.

Who to Call to Replace a Rusted Support Pole

If you notice any rust in the support column, then it’s your cue to take action to get it repaired or replaced. In some cases, you may need an engineer, an inspector, or a remodeling professional. A general contractor can guide you in the right direction after assessing the case. Contact your local general contractor first to inspect and evaluate the situation. 

How Does Basement Support Post Replacement or Repairing Work?

When you notice signs of rust, there are typically two courses of action.

1. Repair the Basement Support Column

If the rust is light and superficial on a post or a Lally column, this means it's not structurally significant, though it might indicate humidity in the basement or crawl space.

To repair the post, a professional will scrape and wire-brush the flaking rust first, then seal it with rust-inhibiting paint. You may want to follow the column repair with a basement waterproofing project to prevent recurring issues.

2. Replace the Basement Support Column

If the column is damaged, then it should be replaced. Serious exfoliating rust and splitting columns can be risky for your home’s structure and stability.

The replacement of the post is a straightforward process. To replace the column, the contractor will put a temporary post between the beam and the floor while cutting the columns off and sliding in new ones in the right position. The contractor will also assess and address the footings; if they have any damaged parts, they will need to be replaced as well. 

A reputable contractor familiar with such repairs will help replace the column. In some cases, you may need to hire a structural engineer to identify the problem, ensure that the building’s structural integrity is intact, and prepare a new design. On average, replacing a steel support beam costs around $3,100.

How to Maintain and Keep a Basement Steel Post From Rusting

After repairing or replacing the support column, there are some things you can do to protect it from further damage:

  • Paint the repaired column with rust-resistant paint, and then add a finishing coat to protect the column from further rust. 

  • Fill the hollow column with concrete, which will help support the basement ceiling.

  • Find the sources of basement humidity or water entry and fix them.

  • Waterproof your basement.

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