Everything You Need to Know About Lally Columns

Marwa Hasan
Written by Marwa Hasan
Updated January 10, 2022
 living room dining area with column
Photo: Iriana Shiyan / Adobe Stock


  • Lally columns are a simple structural solution to support big loads

  • Knocking a wall down is doable with temporary Lally columns

  • Installing Lally columns starts at $2,500

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Whether you’re tearing down a load-bearing wall or solving a sagging flooring problem, a Lally column offers a temporary or permanent solution to hold up structural weight. Learn more about what a Lally column is and how its straightforward design can fortify your home from the basement up.

What Is a Lally Column? 

A Lally column (or a jack post) is a thin, round steel pipe—often found in the basement—to support beams extending over long spans and to prevent any structural problems from occurring. Lally columns are used to correct saggy floors or beams and for additional fortification when remodeling a wall or entryway.

Lally columns also offer a simple and minimalistic look that fits modern home design.

What Are the Benefits of Jack Posts?

Lally posts act as an easy and effective solution for structural quandaries, like faulty floors above crawl spaces and basements. They can also repair squeaky floors, which don't have adequate support from the subfloors. This type of post is quick to install and is easy to cut to size because of its thin steel material.

How Do Lally Columns Work?

Lally columns or jack columns can range in height from about 1 foot to 12 feet or more. Columns that are shorter in height are able to withstand greater loads; Lally columns are sometimes filled with concrete to provide extra strength. They can support permanent structural loads of up to 60,000 pounds.

How to Install a Lally Column?

If you’re repairing a flooring problem or knocking down a wall, you’ll probably need to install some Lally columns, permanently or temporarily. Here are the steps included in Lally column installation:

Preparing the Report

A structural engineer will provide a report with the support your roof needs, which will determine the Lally column’s size, footing, and the number of columns on a certain span. 

Obtaining the Permit

Installing permanent Lally columns will likely need a building permit and an inspection. Your basement contractor should be able to help you file and obtain the necessary permit.

Setting Up the Footing

A Lally column must be attached to the floor, so a contractor will dig down and pour concrete to form the footing. The footer should be at least 2-feet-by-2-feet in size and 12 inches deep. The footing must cure for at least a week before placing the new post.

Placing the Lally Column 

Lally columns can be set up in place of a wall to keep the house structurally sound or fix a sagging beam. Based on the structural engineer report, your contractor can determine the correct size, number, and position of Lally columns.

The contractor should prime and finish the Lally columns before installing them on top of the footings. Some columns are adjustable to allow height modifications. A machine screw-on top or bottom of the column will hold the column tightly in place.

How Much Does a Lally Column Cost? 

Installing a Lally column starts at $2,500. The price depends on many factors, such as basement condition, structural support, and the condition of the existing beams.

What Are the Types of Lally Columns?

Lally columns typically range from 3 feet to 14 feet long. They also come in different types and materials, depending on their function.

Lally Columns Materials

Temporary Lally columns typically use hollow steel. A contractor will fill a steel column with concrete when the column needs to carry a heavy load and stand up to long-term deformation.

Adjustable vs. Non-Adjustable Lally Column

Adjustable Lally columns are usually hollow and act as temporary columns. Adjustable Lally columns consist of two steel tubes that fit together and can be adjusted—up or down—to carry the weight of an unsupported joist or beam. Foundation repair projects often use this type of post. 

Non-adjustable Lally columns are made of steel and typically cut to fit the needed length.

Permanent vs. Temporary Lally Columns

Temporary columns are used to brace the joists of the floor above when removing a wall. Permanent columns are installed under a house, in the crawlspace or basement, to support the structure.

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