Permanent vs. Temporary Support Posts

Permanent vs. Temporary Support Posts – There Is A Real Difference

In my home inspection travels, I sometimes find evidence of past structural repairs in a home in the form of additional structural support in a basement. Depending upon the design and layout of the home, as well as possible actual structural damage that may exist, there are various ways to make repair, however the most common in modern homes is the steel structural support post (also called a column).

There are two types of steel support posts: single-piece and multiple-piece (aka telescopic) columns. Using the improper type of support posts, or installing the proper type of post improperly, can lead to future failure of the structure. Support posts help distribute and carry weight load from one area to another; in most cases, this would be transferring the weight of the home (it’s structure, occupants, the occupants’ belongings, etc.) to the basement floor. These posts normally are connected to a wood or steel I-beam at their top; the outer lateral ends of the wood or steel I-beam bear upon foundation walls.

Generally, only single-piece posts are approved for permanent use. This type of post is steel and hollow and is often filled with concrete when being installed. It must be at least 3″ diameter and should have an ICC or BOCA (reference of building codes) sticker on it. This sticker shows that the post has been evaluated and certified by a third-party testing firm to meet specific design criteria. The sticker is sometimes removed upon the post’s installation. A permanent-rated post will normally have a screwed adjustable end and a flat steel plate (flange) end. In most cases, however this can depend upon the manufacturer, permanent single-piece posts may be installed in either orientation (adjustable end up or down). The bottom end should be cemented or properly bolted into the basement floor and the other end is generally bolted to the steel or wooden beam supporting the home. The International Code Council (ICC) requires that an engineer, architect, or builder be able to prove that the structural posts in a home are sufficient in load carrying capability and that a sufficient number of them are installed in the proper location(s). Permanent posts are also sometimes called “lally columns” although this term is often used for both permanent and temporary-rated posts. Once installed, the threads (if left exposed) should be damaged as to prevent adjustment of the post’s height.

A permanent support post. In most cases, it can be installed in either orientation.

The multiple-piece posts are almost always smaller than 3″ in diameter and are only rated for temporary use. These go by various names including ‘jack posts’. These types of posts are only to be used for temporary uses such as jacking up a home slowly over a period of time. When the jacking (slow lifting of the home) is complete, a permanent column(s) should be installed in place of the temporary post(s) in sufficient locations. Although, in many cases, based upon over 2 decade inspecting homes, these temporary posts are, sometimes, the only type installed and left in place and the job is not actually complete since proper permanent posts are never installed. Sometimes these posts are added due to the need for addition support below a large object above it, such as a water bed or fish tank or piano. It is not the home inspector’s job to determine the need or structural adequacy of support structures. It will be up to the inspector’s discretion whether or not to recommend further evaluation by a structural engineer, for example, if he sees one or two of these temporary posts in a location that may simply be for additional support.

A temporary-only rated support post

This photo from a recent inspection shows numerous temporary-rated support posts installed throughout this basement. Not only are these the wrong posts to use as a permanent repair, this also indicates past structural movement of the home that was likely not properly addressed professionally. This is often a sign of past termite damage or other issues with the main level floor framing.

Temporary-rated posts come in 2 or more pieces; the smaller piece(s) fits within the larger piece. A metal dowel gets inserted through holes in the multiple pieces to fix the overall length. No multi-piece support less than 3″ in diameter has been certified for permanent use. Finding these installed as permanent posts in a home is a defect warranting repair. It also provides evidence of non-professional structural work that was likely not performed with proper engineering and/or permits. Possible damage may exist but may not be visible, especially if the basement has ceilings or insulation installed. Keep in mind that a home inspection is a non-invasive visual examination of the home’s visible and accessible systems and components. Home inspectors do not move or disturb wall/ceiling coverings or insulation.

The issue with temporary-rated support posts is that they are often rated for much less weight load than a permanent-rated post. The weight that a home exerts can allow a temporary-rated post to bend, bow, or break over time. The top plate (flange) should also not be bowed or dished; rather, it should remain straight and, ideally, centered under the overhead beam’s width. Also, don’t assume that just because the post is not visually damaged at this point, that it is necessarily safe to leave in place without repair. Homes get used to the weight distribution of the occupants’ belongings over time. A book case here, a water bed there. A home has likely settled slightly over time due based upon where the current (and prior) owner’s furniture, etc. was located and distributed. A new buyer moving in and often placing their belongings in different locations can sometimes cause future ‘resettlement’ of the home. This may present itself, for example, as new cracks in plaster or drywall or windows/doors that previously operated properly but now stick when trying to open them. In extreme cases, damaged structural components (such as joists, rafters, or support posts) can also be seen. Also, structural posts should not have rust damage (such as from a prior flooded basement) as this can weaken the steel post and can decrease the amount of weight that is can safely bear. Minor paint damage to the post is cosmetic, but a wise home inspector would try to verify that the rust is only in the paint and not in the actual metal. A post with visible rust can be probed by the inspector to determine if the metal itself is still intact or is soft. A damaged structural post should be replaced.

Support posts should be installed vertically and plumb. If the post is not plumb, it likely indicates either a non-professional installation and/or additional structural movement has occurred after the post was installed. In most cases, home inspectors are not licensed structural engineers or architects, so if issues with a home’s structural support posts are found, the inspector should recommend consulting a licensed structural engineer to calculate and determine the needed repairs. If there is visual evidence that structural repairs have been already made within a home (such new floor joists or additional or replaced support posts), even if the repair appears to have been performed properly, the seller should be questioned about the repair, why it was needed, who designed/performed the repair, and obtain warranty paperwork declaring that the contractor was properly qualified. Home inspectors, in most cases, are not properly trained or licensed to declare or certify whether a structural repair is adequate, however, since this would normally require engineering and load calculations which are both outside the scope and standards of a home inspection.

Also, if a lot of rust was noted at the bottom of a steel support post, this indicates that the area got wet in the past, such as due to a past leaking water heater or from exterior water entry. A steel post with more than a small amount of rust should be replaced as rust weakens steel.

Read my Improper Notching and Boring of Joists article, which includes some related issues.

Chapter 5 of the IRC discusses floors and floor structure.

Matthew Steger is a Certified Level 1 Infrared Thermographer, an ASHI Certified Inspector (ACI), and an electrical engineer. He can be reached at matthew@thehomeinspectorsnotebook.com. No article, or portion thereof, may be reproduced or copied without prior written consent of Matthew Steger.