What Is A Lally Column? Differences Between Lally Column And Jack Post
What Is A Lally Column?
A Lally column is a type of structural support column made of thin-walled steel and filled with concrete. It is designed to provide support to beams or timbers stretching over long spans and is commonly used in construction projects.
The steel shell of a Lally column is filled with concrete, which helps to distribute the compression load and prevent local buckling of the shell.
One of the main advantages of Lally columns is their ability to be cut to length on a construction site using basic tools like a plumber’s pipe cutter or a reciprocating saw. However, Lally columns are generally not as strong or durable as conventional structural steel columns.
The name “Lally column” comes from the inventor, John Lally, who owned a construction company that began producing these columns in the late 19th century. While early Lally columns were made with thick-walled steel pipes, modern versions are typically made with thinner 16 gauge steel shells, which are not as strong or resistant to corrosion as older versions.
Modern Lally columns are primarily used as substitutes for wood posts in light-frame wood construction, but can also be used with steel beams.
Types Of Lally Column
Lally columns are versatile structural supports that can be used for both temporary and permanent purposes.
They can be used temporarily to brace the joists of a floor above during a wall removal, and they can also be used permanently to shore up the structure of a house in the crawlspace or basement. They can also be used to hold up heavy weight during major remodels or new window and door installations.
In some cases, they can also be used to correct structural issues and are often allowed to remain permanently in place by local building codes.
How To Install A Lally Column
Installing a Lally column is a simple process that can be done with a few basic tools. These instructions will assume you are installing an adjustable steel Lally column on a solid concrete floor footing and under a solid load-carrying beam such as laminated veneer lumber (LVL) beam.
The first step is to measure the space. Measure the vertical distance to be spanned and choose a Lally column that fits within that range. Keep in mind that there is an adjustment range for the machine screw assembly, typically four inches.
To minimize the elevation of the screw portion, purchase a Lally column that spans as close to the measured distance as possible.
Next, attach the included metal plate to the underside of the LVL beam. Pre-drill holes in the LVL beam to avoid cracking it. Once the location of the metal plate is established, detach it. Then attach the metal plate to the top of the Lally column.
Now it’s time to raise the Lally column. Turn the machine screw on the column so that it is about 1/2-inch short of the distance from the floor to the bottom of the load-carrying beam. Slide the column into place following the manufacturer’s instructions for placement direction.
Turn the screw until the Lally column becomes tight against the beam. The goal is to snug the column into place without jacking up the beam. Once the column is in place and tight, it should provide the necessary support for your beam.
Remove the lever of the adjustment mechanism if it is detachable, and store it securely. However, keep it close by in case adjustments are needed.
Differences Between Lally Column And Jack Post
Lally columns and jack posts are both types of vertical steel members that are used to support horizontal members such as beams, joists and girders. Lally columns are typically used as permanent supports, while jack posts are used as temporary supports.
Lally columns are typically used to provide support to horizontal members such as basement beams, while jack posts are used to correct sagging in horizontal members and require regular inspection.
The height of Lally columns is fixed and cannot be adjusted after they have been installed, whereas jack posts are adjustable to provide support for sagging structural components.
Lally columns can be made of various materials such as steel, wood and concrete, but steel is the most commonly used material.
Wooden Lally columns can be a concern if exposed to the elements, and concrete Lally columns are durable but can be prone to failure. Jack posts are typically made of low-carbon steel and range in length from 3.5 feet to 16 feet, with varying diameters.