Unsafe Telepost column (C) Daniel FriedmanStructural Columns & Piers: Visual Inspection for Defects
     

  • COLUMNS & POSTS, DEFECTS - CONTENTS: How to spot defective structural columns & piers in residential buildings. Examples of proper and improper use of teleposts, jackposts, and Red-I-Posts: adjustable or screw-jack columns. Missing column footings & piers. Missing Lally columns that were removed during remodeling. Use of temporary columns & jackposts, Improper bearing support at Lallys & Teleposts, photographs of structural column mistakes. How to evaluate rust damage to steel columns, posts, adjustable columns in homes
  • POST a QUESTION or READ FAQs about the types of structural column failure in residential & light commercial buildings: inspection, diagnosis, & repair
  • REFERENCES

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This article explains how to notice defective, damaged, improperly supported, or missing structural columns, and other structural column & pier mistakes. Our page top photo shows a telepost used as a "permanent" supporting column. Most models of teleposts or "jackposts" are thin-walled steel and are not designed for permanent use. And all columns require proper bearing support at both the column top and bottom. This leaning, cockeyed jackpost is a structural collapse waiting to happen.

Detecting omissions, such as leaving out a column or it's pier or footing is an important step in learning how to recognize and diagnose various types of foundation failure or damage, such as foundation cracks, masonry foundation crack patterns, and moving, leaning, bulging, or bowing building foundation walls.

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Structural Columns in Residential Buildings: Visual Inspection for Defects

Northridge Meadows Earthquake collapsed column (C) Daniel FriedmanWatch out: This article describes a structural column defects in residential buildings.

Some of these are dangerous and risk collapse. But do not fail to pay careful attention to the structural connections themselves: connections between posts and beams, posts and piers, beams and the floors or ceilings they support.

Connection failure is often the weak link in residential structural movement and collapse.

See DECK COLLAPSE Case Study for an example. FYI we call a 6-inch concrete filled steel column a Lally column after its inventor.

Some folks call these just steel columns, or lolly columns or steel posts.

Proper Use Compared with Misapplication of Temporary Teleposts or Jackposts in Structures

Our photos below show a proper use of a temporary column, telepost, or jackpost - that gray screw-jack to the right of the white-painted steel column I am touching. The second photo at right shows why the temporary column was put in place: the hollow steel column supporting this beam had rusted through at its base, risking collapse. The collapse of a structural steel column is increased if the column is hollow, rather than concrete-filled.

Structural and temporary column uses and defects (C) Daniel Friedman Structural and temporary column uses and defects (C) Daniel Friedman

Thin-walled Steel Teleposts - Maybe Not the Best Choice for Permanent Repairs

Thin walled telepost (C) Daniel Friedman

However what you see is a temporary repair. The rusted steel column should be replaced with a structural column such as a concrete filled steel Lally column that is rated for permanent use.

Our photo (left) shows a thin-walled adjustable column in use in a wet crawl area. The repair contractor installed gravel and then plastic to keep moisture levels down in the crawl space. (The post is probably not out of plumb, that was a tilt in the camera when I shot this photo.)

But notice that the column extends down through the gravel into the presumably wet surface beneath.

Consider that the end of the column is now hidden from view in gravel, that we think this is a recurrent wet area, we can't see if it's wet or not, and more, because this is a tight crawl space, people won't enter it very often to inspect conditions there.

A more durable repair would have been a Lally column. Some builders even prefer to use a pressure treated wood 4x4 post in this sort of location, arguing that it is "rustproof".

Some Teleposts May be Permitted for Permanent Installation

Shown below, some adjustable screw jacks or teleposts such as some Read-I-Post columns are constructed of a heavier-gauge steel and in some jurisdictions they may be approved for permanent use in structures. Often where an adjustable column is permitted for permanent structural use, once it has been properly adjusted in height, its adjusting rod is removed and the screw is tack-welded in place.

Structural and temporary column uses and defects (C) Daniel Friedman Structural and temporary column uses and defects (C) Daniel Friedman

Notice that the installer took care to bolt the Red-I-Post top plate to the beam underside. Let's hope that the beam itself is secured to the floor joists overhead and is protected against lateral movement.

Improper Column Top or Bottom Support, Bearing, or Connections

See our page top photo for an example of a horrible installation of a jackpost that is likely to collapse. Below are more examples of improper telepost installations. At below left we have inadequate bearing surface and no connection between the steel bearing plate and the joist underside. It looks as if the post may also be out of plumb. Boing!

Structural and temporary column uses and defects (C) Daniel Friedman Structural and temporary column uses and defects (C) Daniel Friedman

Which End Goes Up When Installing Screw Jacks & Teleposts?

Our second dangerous telepost photo at above right you can see that the post top screw has bent the steel plate as it pushed into the beam, and the whole assembly is slipping off of the beam and moving to the right. Some installers place screw jacks or teleposts with the screw down against the concrete floor or pier top.

That allows the larger-diameter post "bottom" to be placed up against a steel plate and against the underside of the beam. This "upside down" installation reduces the chances of bending the steel supporting plate and it also places the thick steel screw down on the (often wet) basement or crawl space floor. The thicker steel screw is slower to rust through to the point of collapse than is the thin-walled hollow steel pipe that forms the body of most teleposts.

Supporting Column Location

Improperly placed supporting column (C) Daniel Friedman

It seems obvious that in addition to spacing requirements for supporting steel columns below beams (typicallyi a steel column is placed every eight feet on center in a wood frame two story residential structure), you would also place the column below any splices in the beam.

But a splice in a structural beam also needs resistance to bending upwards. Look closely (click any of our images to see a larger view) and you'll see some nice wood putty in that opening splice joint.

The splice shown in our photo of a home in Portland ME would probably not have bent if it had been located below that floor joist to the right, and had the supporting column placed below the splice as well as below the josits.

Improper Structural Columns Failed at 1994 Northridge Meadows Earthquake

As we also discuss at Earthquake Damage to Foundations, defective supporting columns failed at Northridge Meadows during that 1994 earthquake. It appears that hollow 6" pipes were substituted for concrete filled steel Lally columns under part of the building. Once the fireproofing wrap was installed it was not possible to spot this shortcut by visual inspection.

The hollow columns failed, permitting the upper floors of the structure to collapse. There were fatalities.

Northridge Meadows Earthquake Collapse 1994 (C) Daniel Friedman Northridge Meadows Earthquake collapsed column (C) Daniel Friedman

Here are examples of types of omission that contributed to a structural collapse. During our work at the Northridge Earthquake site in California in 1994 we noticed that some of the supporting Lally columns were hollow rather than concrete filled.

Northridge Meadows earthquake collapse photo showing hollow Lally Column (C) Daniel Friedman

Perhaps due to material shortages or rush during construction, these hollow, and weaker supporting columns were wrapped with a fire-barrier just as were the "real" supporting columns used elsewhere.

Our photos show a section of Northridge Meadows which collapsed during the earthquake. At left you can see that this column was hollow.

Our opinion was that these were defective columns and that they were a factor in the structural collapse during the Northridge earthquake. Other areas of the same complex moved, columns even leaned, but they did not collapse where the columns were of the proper type and were properly connected to the structure.

Other factors in the collapse appeared to include how exterior sheathing had been nailed across or not across certain sections of the building supporting walls. Our list of examples of defects of omission during foundation construction continues below.

See Earthquake Damage to Foundations for more about the defective supporting columns that failed at Northridge Meadows during that 1994 earthquake.

Missing Structural Columns

"Missing" column footings may or may not be a defect depending on design and soil conditions. In some jurisdictions, a poured concrete floor slab may be considered of sufficient thickness and strength to support the column.

Missing lally column  (C) Daniel Friedman

Completely missing structural columns such as a basement Lally column, where an owner has removed the column to open up a basement space being remodeled for use as living area.

Our photo (left), illustrates one way you can spot a missing column: a Lally column top plate remains tacked in place on the under-side of a built-up beam in a basement.

How can we take a photo of a missing structural post or column?

Missing structural column (C) Daniel Friedman

Sometimes you can spot the imprint of this Lally column top plate as a rectangular impression on the underside of a beam even though the steel plate itself was removed. See our photo (left) where you can spot the rectangular imprint of a typical steel Lally column top plate and even two nail holes where the plate had been tacked to the beam underside.

Contextual Clues May Indicate a Missing Structural Column or Post.

A second clue that a supporting column could be missing is contextual: in a conventionally-framed contemporary one family wood structure with a finished basement, especially if the main center girder is a built-up wooden beam, notice that the basement has been converted to a large, open rec-room.

And notice that there is a long span, perhaps sixteen feet, with no supporting post. Perhaps the center girder has been boxed in or covered with paneling and corner molding.

Ask yourself: when this house was built, given that typically I see a Lally column every 8-feet, I wonder if there was one in the center of this room. Was it removed? Was the center girder reinforced with steel? Is there sagging in the floor above?

Pipes are Not Structural Columns

Toy pipes support building (C) Daniel Friedman

Our photo (abpve left) shows a basement girder supported by cute little 2-inch pipes.

We think the installer knew these were not structural-components, because s/he installed these toy "faux-structural" pipes on 5-foot centers.

Settling or Missing Column Footings & Piers Show up As Cracks, Sags, Movement

Failure to compact the soil under a column pier or footing or under a poured concrete slab which has been placed on backfill can result in column settlement.

Our client is pointing to a supporting column in a location where we suspect that crack pattern around the column, combined with a slight but observable depression at the column base area suggests its pier may be settling.

Settling pier below supporting steel column (C) Daniel Friedman Settling pier below supporting steel column (C) Daniel Friedman

When we see a column whose base penetrates the concrete floor slab we know the floor was poured around the column - the column was put in place first. We can't see if a proper pier was installed to support the column base - as is usually the case. Perhaps in the installation we show here, the builder set a 4-inch solid concrete block on (poorly-compacted) fill inside the building foundation, set his post on that, and jacked away. When the fill settles the block settles too, and the column may move downwards, cracking the concrete floor around its base in the pattern we show here.

  • Omitted steel reinforcement - footings missing re-bar or other required steel rods (not visibly detectable after construction) may show up as breaks or cracks and settlement around a post that rests just on the floor slab
  • Missing piers beneath interior or exterior posts may be visible as post settlement or movement downwards through the floor slab without cracks in the slab itself.

How to Evaluate Rusting Steel Structural Columns & Posts That Can Risk Building Collapse

As we also discussed at BASEMENT LEAKS, INSPECT FOR, even a concrete filled steel Lally column can deteriorate enough to lead to building movement or instability. But hollow steel columns such as teleposts and even steel pipes people sometimes think will support a building, heavy exfoliating rust on the columns can lead to crushing or splitting and a structural collapse.

When evaluating the history of water entry in a building we like to look at structural components that have been in place since the building was completed - those are parts that will have been exposed to flooding or recurrent wet floors if water entry has been a problem.

Light superficial rust on a Lally column base is not structurally significant, though it might indicate a history of wet floors in the area. The rust shown at the Lally column base at below left is just a chip, it is insignificant, and we concluded that there was no evidence of a history of wet floors in this basement area. The steel column at below right penetrates the floor slab - we think it may sit on a hidden pier (there was no sign of settling).

But the column surface rust at be;pw right suggests the floor has been wet in this area. We did not think this column had suffered damage that risks it's structural integrity. Click this link to see another photo of rust on the base of a steel column in a basement that we verified over a 12 year life had been subjected to recurrent wet floors but never flooding.

Severe rust damage to steel column (C) Daniel Friedman Crushing steel lally column (C) Daniel Friedman

Comparing Surface Rust to Significant Exfoliating Rust on a Structural Column

But when we see exfoliating rust, some careful poking around to see just how much damage has occurred can help us decide the urgency of replacing the column - and of course fixing the water entry problem . WATER ENTRY in BUILDINGS will help with the latter.

Severe rust damage to steel column (C) Daniel Friedman Crushing steel lally column (C) Daniel Friedman

Example of Structural Steel Column Collapse Due to Rust

At below left we show serious exfoliating rust at the base of a steel column. It's reasonable to infer that this home has been subject to recurrent flooding to a depth of several inches.

Severe rust damage to steel column (C) Daniel Friedman Crushing steel lally column (C) Daniel Friedman

Our second structural rust photo (above right) was very exciting. We were inspecting a house on Long Island when the owner mentioned that she had pumps running 24/7 in the basement to keep Long Island Sound at bay. There was a forest of steel supporting columns (some were just hollow pipes not real Lallys) in this home's basement - all were badly rusted.

As the owner, who was a big person, walked across the floor, the kitchen floor suddenly collapsed and fell down about a foot. We wondered if an earthquake had suddenly struck Long Island.

Trembling we both took another look in the basement. The Lally column shown above and supporting part of the kitchen floor had picked that moment to crush. It was rusted through from repeated flooding.

Also see FLOOD DAMAGE TO FOUNDATIONS.

 

Continue reading at PIER FOUNDATION PROBLEMS or select a topic from the More Reading links shown below.

For problems with settlement of piers below Lally columns see Settlement Cracks in Slabs.

Also see FOUNDATION DEFECTS OF OMISSION - MISSING

Suggested citation for this web page

COLUMNS & POSTS, DEFECTS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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