Lally Columns: Sizes, Footing, Steel Options, and Installation Guide

Lally columns are the round steel structural support columns found in millions of residential basements across North America. Named after their inventor, John Lally, who patented the concept in 1897, these columns have been standard in residential construction for over a century. A lolly column — a colloquial spelling variant used widely in New England — refers to exactly the same product, but the technical and code-compliant term remains lally column in professional contexts.

Selecting the right steel lally column for a basement or crawl space application requires understanding lally column sizes available in the market, the footing requirements that govern how each column is anchored at its base, and the differences between temporary and permanent installation configurations. This guide covers everything homeowners, contractors, and inspectors need to know about lally columns from selection through installation.

What Are Lally Columns and Where Are They Used

Lally columns are hollow or concrete-filled round steel tubes installed vertically to support beam loads in residential and light commercial structures. They are most commonly found in unfinished basements where they support the main carrying beam running the length of the house, transferring floor loads from above down to concrete footings below. The lolly column alternative name is most prevalent in Massachusetts, Connecticut, and surrounding New England states, where the product became particularly common in early twentieth-century residential construction.

Steel lally column construction and materials

A steel lally column consists of a round steel tube with bearing plates welded to the top and bottom. Original lally columns were filled with concrete to increase load capacity and prevent buckling, and many older installations include this concrete fill. Modern steel lally column products use thicker wall steel tubes that achieve comparable or superior load ratings without concrete fill, simplifying installation and recycling at the end of a structure’s useful life. The bearing plates are sized to distribute load across a larger area at both the column base and the beam contact point.

Lally column sizes available in the market

Standard lally column sizes range from 3-inch to 6-inch nominal outside diameter in residential applications, with the 3.5-inch and 4-inch sizes being most commonly specified for typical residential loads. Length options typically range from 6 feet to 12 feet in standard increments, with adjustable versions available for installations where the precise finished height is not yet determined. Load capacity for lally column sizes varies by diameter, wall thickness, and unsupported height — manufacturers publish detailed load tables that installers must consult when selecting columns for specific structural applications.

Lally Column Footing Requirements

Every lally column installation requires an adequate concrete footing at the base to distribute the concentrated point load from the column across a sufficient area of soil or slab. The lally column footing must be sized based on the load carried by the column and the bearing capacity of the soil or existing concrete slab. Residential building codes typically require a minimum footing size for basement columns, but loads above typical residential values require engineering calculations to determine adequate footing dimensions.

A lally column footing in a poured concrete basement typically involves breaking through the existing slab, excavating to undisturbed soil, pouring a new concrete pad of appropriate dimensions, and allowing it to cure before installing the column. In older homes with dirt-floor basements, the footing is poured directly on the soil at sufficient depth to reach undisturbed bearing material. Code requirements for lally column footing dimensions vary by jurisdiction, and local building permits are typically required before installing or replacing basement support columns.

Adjustable vs. Fixed Lally Columns

The choice between adjustable and fixed lally columns depends on the phase of construction and the intended permanence of the installation. Adjustable lally columns with threaded adjustment mechanisms allow height setting during installation and limited re-adjustment afterward, which is useful in situations where settling or beam deflection may require post-installation correction. Fixed lally columns are cut to precise length at the shop or field and provide maximum rigidity once installed, which is preferred in finished basement spaces where long-term stability without any movement is essential.

Many jurisdictions distinguish between adjustable lally columns approved for temporary use during construction and those approved for permanent installation. The approval status depends on the column’s load rating after adjustment and whether the adjustment mechanism can maintain its rated capacity under sustained load without creep or loosening. Always verify the approval rating for permanent installation when selecting adjustable lally columns for a code-compliant permanent application.

Installation Best Practices for Lally Columns

Installing lally columns correctly requires verifying that the footing is adequate, the column is plumb, and the beam above is properly supported throughout the installation process. When replacing an existing column, temporary shoring must be installed before the old column is removed to maintain support for the beam and the floor structure above. Use a spirit level on two perpendicular faces to verify plumb before finalizing the installation, as even a small deviation from vertical reduces the column’s effective load capacity and creates long-term structural concerns.

The connection between a lally column and the beam above should be a positive bearing connection — the column top plate should be in full contact with the beam across its entire bearing area. Shimming minor gaps with steel shim plates is acceptable practice; wood shims are not appropriate in this application because wood is subject to crushing and compression under sustained load. Document the installation with photographs and retain records of the load calculations and product specifications used in the installation for future reference by inspectors or purchasers of the property.

Safety recap: Never remove a lally column without first installing adequate temporary shoring to support the beam and floor structure above. Consult a licensed structural engineer before modifying any load-bearing column installation, particularly in older homes where the original structural design documents may not be available.