The Foundation Crack Bible - Foundation Cracks, Leans, Bulges, Settlement: Inspecting Foundations for Structural Defects - Detection, Diagnosis, Cause, Repair InspectAPedia® -
Visual inspection of foundations
Types of foundation damage
Extent of foundation damage
Concrete foundation cracks, damage
Masonry block foundation cracks, damage
Stone foundation bulges & movement
Photographs of foundation crack patterns
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This document describes how to recognize, diagnose & repair various types of foundation failure or damage, such as
foundation cracks, masonry foundation crack patterns, and moving, leaning, bulging, or bowing building foundation walls. Types of foundation cracks, crack patterns, differences in the meaning of cracks in different foundation materials, site conditions, building history,
and other evidence of building movement and damage are described to
assist in recognizing foundation defects and to help the inspector separate cosmetic or low-risk conditions from
those likely to be important and potentially costly to repair.
The photo at page top shows a bowed masonry block foundation wall with horizontal cracking that occurred due to earth loading at the time
of construction, probably by vehicles driving too close to the foundation wall shortly after it was constructed. At this website
we explain how it is sometimes possible to be confident about the cause of foundation damage which in turn helps assess
the risk presented to the building.
Photographs of types of foundation cracks and other foundation damage: we have a large library of photographs which
are constantly adding this website. Contact us if you have questions, suggestions, or content contributions for this material. We are pleased to give full citation credit for technical reviewers and content contributions.
Methods & Procedures for Evaluating Residential Structural Foundation Cracks, Movement, & Condition
This document is for building owners, professional or licensed home inspectors, foundation repair companies, foundation engineers, architects,
and other building professionals concerned with residential property
masonry foundation failure detection, diagnosis, and repair.
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.
The photo above shows a cracked, bulged, leaning stone foundation wall at the edge of an embankment - a condition we discuss further
at this website.
Foundation Inspection Objectives
Home inspectors, building code compliance inspectors, and general building contractors are often able
to recognize possible foundation or other building problems which may be costly or dangerous,
thus requiring the intervention of an expert
foundation repair company or foundation design engineer.
These early visitors to a building site, most often the home inspector,
see a very large number of in-service field conditions leading to building failures.
Foundation inspectors can,
without performing any engineering calculations or analysis,
learn to recognize signs of important foundation or other structural problems developing well before
forensic engineers and foundation experts are asked to
design a repair and almost always well before the actual occurrence of a catastrophic building failure.
This breadth of field inspection experience and education, combined
with an informed and careful building inspection, provide a valuable
first line of defense for building owners and occupants who may be facing previously unrecognized costly or
dangerous foundation damage.
Foundation inspections are conducted to identify & document potential costly or dangerous conditions. The inspection
must consider many factors beyond the obviously visible condition of the foundation, such as attending to site conditions,
evidence of the history of building movement, and the type, location, and extent of cracking and movement. This data, combined
with education and experience, permit a knowledgeable foundation inspector to advise the client about the urgency of
foundation repair and the type of repair that may be needed.
Accountability: the inspector is accountable for visible portions of the foundation
and for recognizing signs of defects. In some circumstances this may include
invisible or hard-to-see conditions for which there are nonetheless adequate clues: contextual, historical,
or other visible secondary evidence.
Action: If appropriate, the inspector may suggest further evaluation/repair including invasive methods such as removing finish
materials that cover the foundation, outside excavation, the employment of a foundation engineer, foundation repair company,
a test firm to make soil borings, or other investigative measures.
Dangers: Since certain masonry structure defects, such as bulged above ground brick masonry walls, can lead to sudden
precipitous and catastrophic collapse, dangerous conditions may be present at some properties. While there are often
hidden conditions which can disguise building conditions, the ability to
recognize those potentially urgent or dangerous conditions which can be detected is important in a foundation inspection.
Note: In-service field conditions refers to the state of repair of a building or its components
while the building is in-use. Building construction standards, engineering and architectural design, and building
code compliance have traditionally dealt either with advance specifications for a building which is
to be constructed, or with the forensic examination of a building or component after it has failed.
The science and practice of in-se vice building inspections and building conditions provide
an important but different base of experience about the way in which
buildings and building components fail, the causes of building failures, and the detection of
clues indicating that failures are developing. In-service building inspections provide an opportunity to detect
evidence of developing construction failures which (usually) have not yet reached such dire conditions as to
be obvious to the lay person.
The home inspection profession (contrasted with the "home inspection industry")
focuses on in-service field conditions and as such has developed its own unique education, standards, ethics,
and practices. Yet it also requires an understanding
of design, codes, and building standards as well as traditional failure analysis.
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
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.
Carson Dunlop, Associates, 120 Carlton Street Suite 407, Toronto ON M5A 4K2Toronto. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
"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
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. *
*These reviewers have not returned comment 6/95
"Quality Standards for the Professional Remodeling Industry", National Association of Home Builders Remodelers Council, NAHB
Research Foundation, 1987. See our books at "Structure" at the InspectAPedia Bookstore
Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.
FOUNDATION DAMAGE SEVERITY - How to Evaluate the Significance or Amount of Foundation Movement when a foundation is leaning, bulging, bowing, or settling
See FOUNDATION DAMAGE SEVERITY for our discussion of how to evaluate and report the severity of building foundation damage. A few examples are provided just below.
Historical data is a key observation or data that needs to be collected to assess the significance of any evidence of foundation movement
New or sudden foundation movement: If foundation cracking or movement is new, recent, or sudden: serious, prompt action is needed and you should consult an expert, in particular
if the amount is more than trivial. Trivial movement would be the discovery of a hairline crack (less than 1/16" in width) or a shrinkage crack
in a building foundation wall or floor slab. A word of caution: sometimes a crack has been present for a long time at a building but has simply
not been noticed by the building owner or occupants. The first time such a crack is seen it may be mistaken for "new" and "sudden" when that is
not the case. See our discussion of SHRINKAGE vs EXPANSION vs SETTLEMENT.
Recurrent foundation cracking or movement: action is probably needed since recurrent movement can lead to cumulative damage to some structures
even if the amount of movement is not great. In particular, if you have made cosmetic repairs to a foundation or to plaster or drywall finished
areas above and supported by such a foundation you may see that the cracks you repaired have simply recurred.
Long term, continuing, but slow foundation movement: action may be needed, particularly if the effects of long term foundation
movement are cumulative.
Initial foundation cracking or other limited damage occurring at time of construction such as foundation
cracks in a masonry block wall which occurred during backfill may not need other than cosmetic repairs, in particular if there is no
evidence of subsequent foundation movement and still more likely if the initial damage and amount of movement was minor (say less than 1/2"
of inwards foundation wall bulge in the cracked areas.)
Foundation damage due to being struck: in this case the foundation will certainly need repair if the damage
to it was extensive with collapsed or severely dislocated components. Trivial foundation damage, say cracking a masonry block
on the corner of a garage with no basement below, is less likely to be significant.
Initial foundation settlement may not require additional repair. A hairline to 1/16" vertical crack in a concrete wall or
similar dimension step cracking in a masonry block wall may need cosmetic and sealant repair (to reduce leakage through the wall,
but if the initial amount of settlement was very small and is not ongoing, repair is unlikely to be needed.
These examples of foundation damage are almost always very important and need expert attention
Dislocated gas, plumbing, or electrical wiring or piping: NOTE: ANY foundation damage or crack associated with significant displacement of original structural or mechanical (gas/sewer lines) components is
likely to be significant. Even slight displacement is significant if mechanical systems may be unsafe (earthquake). Dislocated gas lines means
gas leaks are likely and there is serious damage of catastrophic explosion. Vacate the property, and immediately call the gas company from a telephone that is
not exposed to gas fumes.
Dislocated or broken structural connections such as a building which has shifted off of its foundation or has broken sill bolts or straps
connecting the foundation to the building framing needs expert investigation and repair.
Bulging foundation walls in response to area flooding are at risk of collapse; temporary support of the building and other measures
to relieve stress on the foundation may be needed. Do not delay in seeking expert advice in this situation.
This list is not complete. Suggestions welcomed.
Foundation Inspection Standards - ASHI Standards of Practice (American Society of Home Inspectors)
Daniel Friedman - ASHI Member (1986-2006) - building failures researcher.
"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
Arlene Puentes, 845-339-7984, is an ASHI member and a licensed home inspector in Kingston, NY, and has served on ASHI national committees as well as HVASHI Chapter President. Ms. Puentes can be contacted at ap@octoberhome.com.
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*
*These reviewers have not returned comment 6/95
Technical Edits, Changes, Amendments to This Document
09/23/3008 adding crawl space safety warnings and crawl space dyrout procedures
10/06/2009 adding flood damage to foundations - a flood damage investigation case suggests pre-existing cracks
08/03/2007 adding text, illustrations, content, organization changes, citations to authority
06/07/2007 adding text, illustrations, content
5/30/2007 editing to add content on foundation crack repair
9/23/2006 editing to clarify text and add content; Technical review (partial) by Arlene Puentes.
4/17/2006 editing to clarify text in several sections.
More Information on Building Diagnostic Inspections and Repairs
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 reprints available from some inspection tool suppliers)
Design of Wood Structures, Donald E. Breyer, McGraw Hill, 1988 ISBN 0-07-007675-8
Building Failures, Diagnosis & Avoidance, 2d Ed., W.H. Ransom, E.& F. Spon, New York, 1987 ISBN 0-419-14270-3
Guide to Domestic Building Surveys, Jack Bower, Butterworth Architecture, London, 1988, ISBN 0-408-50000 X
ASHI Training Manual - not recommended: incomplete, inaccurate, overpriced--DF
The Home Reference Book and other Manuals from Carson Dunlop, Home Pro, T.I.E., Inspection Training Associates (Home Inspection training/report firms)
"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
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