How to Detect, Diagnose, & Evaluate Combinations of Foundation Movement, Bulges, Cracks, Leaning InspectAPedia® -
How to Evaluate and Diagnose Complex Combinations of Foundation Movement Cracks, Bends, Leans, or Shifts in Foundation Walls
Different causes of foundation leaning, bulging, cracking, creeping, tilting, sliding, or other movements, what they look like, how to fix them.
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This chapter of the "Foundation Crack Bible" discusses in detail the recognition of different types and causes of complex or combined building foundation
movement and foundation damage. We distinguish among vertical movement, horizontal movement, leaning, tipping, bending, differential and
uniform settlement, earthquake and storm damage, and other foundation damage patterns.
This article series describes 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.
To be used properly, this information must be combined with specific
on-site observations at the particular building in order to form a reliable opinion about the condition of that building's foundation. Anyone having
concern regarding the structural stability, safety, or damage of a building, foundation or other components, should consult a qualified expert.
Photographs of types of foundation cracks and other foundation damage: we have a large library of photographs which
we're in process of adding to this document. Pending completion of that work, contact the author if assistance is required.
Combinations of Foundation Wall Movement, Horizontal & Vertical Crack Patterns Occuring Together
Wall bulge and step cracking
Step cracks may also be present in bulged, leaning, or horizontally pushed foundation walls if they were constructed
of brick or masonry block, or possibly (though less common) of stone.
In fact since the building foundation corners are stronger
than the center portions of the foundation wall (the opposing wall at right angle resists movement of the wall being pushed),
wall bulges, leans, and cracks tend to occur towards the center of the wall, resulting in step-cracking closer to
the ends of the same wall.
In the photograph above, frost push has bulged the center of the foundation wall inwards; as the forces of wet earth
and or frost pushing on the upper 1/3 of this foundation wall were applied at the center of the wall, the wall bulged
inwards and cracked horizontally at the point of most pressure.
As the same forces causing this wall to bend were exerted
closer to the building corners, the wall cracked in the step-crack pattern clearly marked in this picture by the "repairs"
which have been done by filling the cracked joints. If the total amount of wall movement was minor and if the outside
source of pressure (water and frost) has been corrected, further repair or reinforcement may not be needed.
Combinations of Foundation Wall Movement During Collapse
In this collapsing foundation illustration, the masonry block wall has bulged inwards, portions are leaning inwards, and
some of the courses of masonry blocks have slid horizontally to extend over their neighbors. All three movements are present,
and of course this wall needs to be re-built.
If you think of a concrete block wall as a stack of "shoe boxes" that you're
holding between your hands, and if your friend begins to push inwards on the middle shoe box, you can keep the stack
of boxes intact for a while.
But eventually your accomplice applies enough horizontal pressure to the center box that
the stack begins to bend. When the bending stack of boxes (or concrete blocks) bends inwards far enough to
pass a critical point, the whole stack simply pops inwards and collapses.
This is how a concrete block wall can
collapse suddenly when pressure on it builds past a critical point. (The same wall, if reconstructed with the addition of
vertical steel reinforcing rods and concrete will be much stiffer against the same forces.)
Examples of Flood Damage to Building Foundations
Flood damaged building foundation walls: just as earth pressure or the increased pressure from wet earth can lead to
foundation damage or even collapse, flooding around buildings can lead to foundation damage or collapse from a combination
of pressure on foundation walls and perhaps loosening of supporting soils.
In flood prone areas local building codes may call
for the installation of flood ports on building foundation walls to reduce the risk of building collapse. The principle of
the flood vent is simple: in response to high water surrounding a building the flood vent opens to permit water to enter the building basement or crawl space, thus equalizing pressure on both sides of the foundation and reducing the chances
of foundation collapse.
Examples of other step cracks occurring in masonry walls or masonry foundations
Other step cracks will of course also occur in building masonry block foundation walls and in
brick masonry walls that are not leaning
or bulging particularly, where frost or settlement have been causing an "up and down" movement in the foundation or footing.
We will also encounter step cracks where earth pressure or frost have pushed such a wall horizontally, breaking the
masonry courses near a corner or wall-end in a stair-step pattern such as we see in this little example of water and frost
damage to a brick retaining wall.
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Additional technical contributors & reference sources for this article are listed below.
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"Concrete Slab Finishes and the Use of the F-number System", Matthew Stuart, P.E., S.E., F.ASCE, online course at www.pdhonline.org/courses/s130/s130.htm
Sal Alfano - Editor, Journal of Light Construction*
Thanks to Alan Carson, Carson Dunlop, Associates, Toronto, for technical critique and some of the foundation inspection photographs cited in these articles
Terry Carson - ASHI
Mark Cramer - ASHI
JD Grewell, ASHI
Duncan Hannay - ASHI, P.E. *
Bob Klewitz, M.S.C.E., P.E. - ASHI
Ken Kruger, P.E., AIA - ASHI
Bob Peterson, Magnum Piering - 800-771-7437 - FL*
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
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book 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. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
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.
"Avoiding Foundation Failures," Robert Marshall, Journal of Light Construction, July, 1996 (Highly recommend this article-DF)
"A Foundation for Unstable Soils," Harris Hyman, P.E., Journal of Light Construction, May 1995
"Backfilling Basics," Buck Bartley, Journal of Light Construction, October 1994
"Inspecting Block Foundations," Donald V. Cohen, P.E., ASHI Reporter, December 1998. This article in turn cites the Fine Homebuilding article noted below.
"When Block Foundations go Bad," Fine Homebuilding, June/July 1998
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.
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