How to Install Basement Jack Posts

Dale Yalanovsky

A jack post is an adjustable steel column that is generally used as a means of support for overhead beams. In the United States they are only to be used as a temporary support system and must eventually be replaced by a permanent system.


Most jack posts have pre-drilled anchoring plates on both the top and the bottom for added stability. Holes can be drilled in the cement floor to anchor the post, while lags can be screwed into a support beam to attach the upper jack post plate.

Although there are many makes and models of jack posts, the jacking mechanism works in essentially the same fashion for all of them. Placement and mounting, however, must be determined by the user and the situation in which the jack post is needed.

  1. Place the jack post in position. The base must be level and placed solidly on the basement floor. Use a level to ensure that both the base and the sides are level and plumb.

  2. Extend the upper portion of the post as far as it will go. On many types, a pin is removed and the upper portion is extended as close as it can be to the overhead beam. Replace the pin when the extension is complete.

  3. Adjust the jack by turning a central screw or bolt mechanism. Depending on the jack design, there will either be a built-in handle or a nut that must be turned by a wrench. Turn the screw mechanism until the top of the jack post firmly contacts the overhead support beam.