Adjustable steel columns, also known as screw jacks, are hollow steel columns designed to provide temporary structural support. An attached threaded screw mechanism is used to raise and lower the height of the post. They are usually found in basements. Screw jacks can be made as multi-section assembles, sometimes called telescopic steel columns, or as single-piece columns.
All support columns must be larger then three inches. Temporary columns smaller than three inches violate the IRC, although they are not necessarily defective. A 2½-inch column may be sufficient to support the structural load above it, while a 4-inch post can buckle if the load exceeds the structural capacity of the post. Structural engineers, not home inspectors, should evaluate whether adjustable columns properly sized. The post must be protected by rust-inhibitive paint. The column should be straight. The maximum lateral displacement between the top and bottom of the column should not be more then one inch. The column should also not flex or bend at its center point. Bending or flexing is an indication that the column cannot bear the weight above it. The column is not mechanically connected to the floor. Inspectors may not be able to confirm whether a connection between the post and the floor exists if this connection has been covered by concrete. The post should be mechanically connected to the beam above to provide additional resistance against lateral displacement. No more then three inches of the screw thread is exposed
Home inspectors should inspect adjustable steel columns for problems, although a structural engineer may be required to confirm serious issues.