How to Distiguish Foundation Bulging vs. Leaning InspectAPedia® -
How to Distiguish Foundation Bulging vs. Leaning Movement by Type & Location of Cracks & Bends in Foundation Components
Different causes of foundation leaning, bulging, cracking
How to Evaluate and Diagnose Foundation Movement by Type & Location of Cracks, Bends, Leans, or Shift in Foundation Components
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This chapter of the "Foundation Crack Bible" discusses in detail How to Distiguish Foundation Bulging vs. Leaning Movement by Type & Location of Cracks & Bends in Foundation Components. 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.
How to distinguish between a "bulged" foundation wall and a "leaning" foundation wall, and why we care
Why distinguish between leaning and bulging foundation walls?
We care about the distinction between leaning and bulging because understanding the location and pattern of
foundation wall cracking or movement may help us diagnose its cause and thus may help us understand what actions
are needed to stop further foundation movement or perhaps to decide on a course of repair or reinforcement of the wall.
For example, recognizing that a foundation wall has bulged inwards at about the depth of the frost line at a building
may tell us that the root cause of that particular foundation movement was frost pressure from spillage of roof
runoff too close to and along the building wall.
The same forces produce different effects on poured concrete walls compared with masonry block, brick, or stone walls
Even a concrete wall which is bulged is likely to be cracked horizontally, though perhaps not in
such a straight line. But a bulged reinforced concrete wall would be very rare unless perhaps the concrete wall bulged, or its
forms bulged, during the time that the concrete was being poured and was still wet.
It's more likely that a reinforced concrete
wall will be caused to lean or to shift horizontally while a masonry unit wall or stone wall is likely to be bulged and
cracked by the same external forces.
Characteristics of a bulging foundation wall
If our measurements anywhere between the floor and the top of the wall is greater than the distance measured (wall to string)
at the floor bottom and at the wall top then the wall is "bulged" inwards at that point.
If the wall is masonry block in construction we'd
expect to see horizontal cracks in one or mortar joints in the bulged area, with the widest horizontal crack at or close to the
point of greatest inward bulge.
If all of our measurements of inwards movements in the foundation wall increase in distance (wall to string),
from floor up towards the top of the wall,
the wall is leaning inwards.
In this case we'd expect to not see horizontal cracks (if the wall is masonry block, for example).
Watch out: in some cases a foundation wall may not lean in the direction you expect.
For example a reinforced masonry block
wall or poured concrete wall which has been pushed inwards by earth loading might move inwards at the bottom of the wall rather than at the top.
The bottom of the wall will have been pushed in to the building basement or crawl space and the top may
actually begin to lean out and may even become visible outside, protruding out past the building framed wall.
Earthquake
damage which shifts a building off of its foundation can also produce something that looks like and can be mistaken for
this condition.
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Additional technical contributors & reference sources for this article are listed below.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
"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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