In terms of a home’s structure, Lally columns are round thin-walled steel columns that run vertically to provide support to beams in a home. The shell of the column itself is filled with concrete, which helps to prevent buckling. The advantage of this type of structure is it can be easily customized at a construction site. While they are not as durable or strong as traditional structural steel columns, they do serve their purpose for different places in a home during construction. They are meant to be temporary.
These columns also can be used in basements or crawlspaces in order to support floor joists that are sagging or not secure. Never use these for jacking up any weight as they most likely will not hold the item for a long period of time. Small Lally columns oftentimes can hold no more than 18,000 pounds.
Modern Lally columns are made with 16 GA shells and are lower in strength then the older design. They also are subject to more damage in moist environments. Home contractors often use them to substitute wood posts in light-frame wood construction to save on money.