One structural defect that NJ home inspectors encounter almost on a weekly basis is the improper use of adjustable columns as permanent supports. I have to say that we encounter these a lot. These columns are also referred to as Screw Jacks and Beam Jacks. Whatever name there are called these columns are not designed for the permeant support of a structure. They are for temporary support only but are often found as the permanent support structure in a home.
What I am writing about here are two-piece columns that come apart. One length of the column enters the other section of the column, and the two sections are secured with a solid pin. There are many types of non-split adjustable columns in use that are approved for permanent use however, this discussion will center around the two-piece adjustable columns that NJ home inspectors encounter very often.
What are the components of a jack post? They are usually made up of two steel lengths that are hollow. There is an adjustment screw at the top of the column. The smaller diameter tube slides into the larger section of the column tube. Once the sections are roughly set to length steel pins are installed through precut holes in both the narrow and the wider tubes. The screw at the top of the column then can be adjusted to fit tightly under the beam. There are steel plates that are installed in-between the screw and the underside of the beam and the bottom of the column and the cement floor.
Home inspectors in New Jersey should identify split type jack posts or screw jacks as a structural defect. These columns are just not approved for permanent load carrying. The International residential code indicates that any permanent column has to be at least three inches in diameter. These manufactured jack posts are smaller than three inches in diameter and thus do not meet the threshold for a permanent support column
One of the issues with these columns is that they are not rust protected. The international residential code requires that all surfaces both inside the column and on the column exterior be coated with a rust inhibiting paint. These adjustable columns are not protected from rust. Rusting to steel can cause weakening of the metal and eventually cause failure. The thin adjustable columns are not designed to be exposed to high moisture over long periods. If a sudden column failure occurs then a chain reaction of failures can also occur causing significant structural damage, injury and possible loss of life.
Another issue often encountered is that the temporary columns are not tied into the beam or the floor. The top plate of the columns should be attached to the beam in order to help avoid lateral displacement.
Why are these columns so often used in homes? Because they are inexpensive and easy to find and install. Screw jack type columns can be found at any hardware store for an inexpensive price as compared to a permanent support column. Many homeowners will opt for the less expensive option even though these columns are not for permanent use. There is also a lot of confusion regarding the purpose of these columns. Most consumers think that these are permanent columns because they see them in place all the time. The column manufacture also aids in this confusion because they do not indicate on their packaging that these columns are not designed for permanent use. Column manufacturers want to sell columns of course and leave it to the consumer to research their intended purposes which of course few do.
There are also professional contractors who install these columns either out if ignorance or on purpose for cost savings. Using telescoping columns can save the contractor time and money because they are easy to install as compared to the permanent columns and much less expensive than permanent support columns. Often these telescoping columns are just resting on the basement floor slab without the proper footings. A lot of money and time can be saved if footings are not installed with the project. Often Municiple inspectors will approve the columns because even they have been accustomed to seeing them in the field.
These adjustable columns do have their purpose it is just not for permanent structural support. The purpose of these columns it to temporarily support a structure while a permanent cement filled column and proper footing are being installed. They are to be removed once the permanent columns are installed and in place.
Home inspectors in NJ should explain that the use of split adjustable support columns are not allowed for permanent use under a structure. Home inspectors should recommend that any temporary columns be replaced with permanent support columns in order to avoid hazards and damage.