POST a QUESTION or READ FAQs about the types of structural column failure in residential & light commercial buildings: inspection, diagnosis, & repair
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Structural column defects:
This article explains how to notice defective, damaged, improperly supported, or missing structural columns, and other structural column & pier mistakes.
Here we will discuss missing structural column or post footings & piers, missing Lally columns that were removed during remodeling, use of temporary columns & jackposts, Improper bearing support at Lallys & teleposts. We include photographs of structural column mistakes. We explain how to evaluate rust damage to steel columns, posts, adjustable columns in homes,
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.
We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.
Structural Columns in Residential Buildings: Visual Inspection for Defects
This article describes a structural column defects in residential buildings. Larger structures using supporting columns and piers certainly require additional professional design from a civil or structural engineer or similar design professional.
Watch out: Some of these residential column or post defects 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.
Watch out: The collapse of a structural steel column is increased if the column is hollow, rather than concrete-filled.
Thin-walled Steel Adjustable Teleposts - Maybe Not the Best Choice for Permanent Repairs
However what you see in the photographs above 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 next structural column photo (above ) 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 Adjustable Teleposts May be Permitted for Permanent Installation
Shown here, 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.
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.
Pipes are Not Acceptable as Structural Columns
Our photo (above 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.
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!
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
It seems obvious that in addition to spacing requirements for supporting steel columns below beams (typically 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 joists.
Improper (Hollow) Structural Columns Failed at 1994 Northridge Meadows Earthquake
As we also discuss at EARTHQUAKE DAMAGED 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.
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.
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. In the second Northridge Meadows building collapse photograph just above 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.
Watch out: in a structural brick wall-built building, if one or more main beams lose their support, sag, and collapse, there is a high risk of a total catastrophic structural collapse.
Settling or Missing Column Footings & Piers Show up As Cracks, Sags, Movement
Missing Post or Column Footings / Piers
"Missing" column footings or piers 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.
Of course one cannot, without special equipment, "see" through a concrete slab to determine whether or not a pier was provided or required below a post. But in some instances there will be compelling evidence of a missing pier under the slab.
Settlement Crack patterns that surround the bottom of a post often indicate slab settlement around an existing pier. You might confirm that hypothesis by noting that the post itself has not settled and that the slab outside of the surrounding cracks is lower than the slab around the post bottom.
Settlement Crack patterns around a post or column can also indicate a missing or settling pier if the slab concrete around the post is lower than the surrounding floor.
Post settlement: On occasion we see evidence of post settlemnt through the slab even though the slab itself shows no cracks nor settlement around the post. A classic example of this situation is the presence of a gap between the post top and the beam that it should be supporting. (Remember to check that no one has removed a shim that was previously in that space.)
What causes pier or slab settlement around or below a post?
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.
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.
Evaluate RustedSteel Structural Columns & Posts
Please see COLUMN / POST RUST DAMAGE where we have moved and expanded the discussion of rust or dent damage to structural steel columns, posts, or jackposts.
Continue reading at COLUMN / POST MISSING or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Arlene Puentes, ASHI, October Home Inspections - (845) 216-7833 - Kingston NY
Greg Robi, Magnum Piering - 800-822-7437 - National*
Dave Rathbun, P.E. - Geotech Engineering - 904-622-2424 FL*
Ed Seaquist, P.E., SIE Assoc. - 301-269-1450 - National
Dave Wickersheimer, P.E. R.A. - IL, professor, school of structures division, UIUC - University of Illinois at Urbana-Champaign School of Architecture. Professor Wickersheimer specializes in structural failure investigation and repair for wood and masonry construction. * Mr. Wickersheimer's engineering consulting service can be contacted at HDC Wickersheimer Engineering Services. (3/2010)
*These reviewers have not returned comment 6/95
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Diagnosing & Repairing House Structure Problems, Edgar O. Seaquist, McGraw Hill, 1980 ISBN 0-07-056013-7 (obsolete, incomplete, missing most diagnosis steps, but very good reading; out of print but used copies are available at Amazon.com, and reprints are available from some inspection tool suppliers). Ed Seaquist was among the first speakers invited to a series of educational conferences organized by D Friedman for ASHI, the American Society of Home Inspectors, where the topic of inspecting the in-service condition of building structures was first addressed.
Design of Wood Structures - ASD, Donald E. Breyer, Kenneth Fridley, Kelly Cobeen, David Pollock, McGraw Hill, 2003, ISBN-10: 0071379320, ISBN-13: 978-0071379328 This book is an update of a long-established text dating from at least 1988 (DJF); Quoting: This book is gives a good grasp of seismic design for wood structures. Many of the examples especially near the end are good practice for the California PE Special Seismic Exam design questions. It gives a good grasp of how seismic forces move through a building and how to calculate those forces at various locations.THE CLASSIC TEXT ON WOOD DESIGN UPDATED TO INCLUDE THE LATEST CODES AND DATA. Reflects the most recent provisions of the 2003 International Building Code and 2001 National Design Specification for Wood Construction. Continuing the sterling standard set by earlier editions, this indispensable reference clearly explains the best wood design techniques for the safe handling of gravity and lateral loads. Carefully revised and updated to include the new 2003 International Building Code, ASCE 7-02 Minimum Design Loads for Buildings and Other Structures, the 2001 National Design Specification for Wood Construction, and the most recent Allowable Stress Design.
Defects and Deterioration in Buildings: A Practical Guide to the Science and Technology of Material Failure, Barry Richardson, Spon Press; 2d Ed (2001), ISBN-10: 041925210X, ISBN-13: 978-0419252108. Quoting: A professional reference designed to assist surveyors, engineers, architects and contractors in diagnosing existing problems and avoiding them in new buildings. Fully revised and updated, this edition, in new clearer format, covers developments in building defects, and problems such as sick building syndrome. Well liked for its mixture of theory and practice the new edition will complement Hinks and Cook's student textbook on defects at the practitioner level.
Straw Bale Home Design, U.S. Department of Energy provides information on strawbale home construction - original source at http://www.energysavers.gov/your_home/designing_remodeling/index.cfm/mytopic=10350
More Straw Bale Building: A Complete Guide to Designing and Building with Straw (Mother Earth News Wiser Living Series), Chris Magwood, Peter Mack, New Society Publishers (February 1, 2005), ISBN-10: 0865715181 ISBN-13: 978-0865715189 - Quoting: Straw bale houses are easy to build, affordable, super energy efficient, environmentally friendly, attractive, and can be designed to match the builder’s personal space needs, esthetics and budget. Despite mushrooming interest in the technique, however, most straw bale books focus on “selling” the dream of straw bale building, but don’t adequately address the most critical issues faced by bale house builders. Moreover, since many developments in this field are recent, few books are completely up to date with the latest techniques. More Straw Bale Building is designed to fill this gap. A completely rewritten edition of the 20,000-copy best--selling original, it leads the potential builder through the entire process of building a bale structure, tackling all the practical issues: finding and choosing bales; developing sound building plans; roofing; electrical, plumbing, and heating systems; building code compliance; and special concerns for builders in northern climates.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones