The Foundation Crack Bible - Foundation Cracks, Leans, Bulges, Settlement: Inspecting Foundations for Structural Defects - Detection, Diagnosis, Cause, Repair
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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.

© Copyright 2009 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links 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.

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.

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.

...

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FOUNDATION DIAGNOSIS - how to inspect and diagnose foundation problems, in-depth diagnosis, and evaluation of all types of structural and non-structural cracks in residential foundations [Brick, Concrete, Masonry Block, Stone]
INTRODUCTION
EARTHQUAKE DAMAGED FOUNDATIONS - examples of earthquake-damaged building foundations
FOUNDATION CONSTRUCTION TYPES - identify different foundation types, construction materials, effects of sequence of construction
FOUNDATION INSPECTION METHODS - what to look for when inspecting any building foundation
FAILURES by FOUNDATION TYPE & MATERIAL- unique failure characteristics of each foundation material
  Block Foundation & Wall Defects
  Brick Foundation & Wall Defects
  Brick Thermal Expansion Cracking
  Concrete Poured Foundation Wall & Slab Defects
  Concrete Pre-cast Foundation Defects
  Stone Foundation Defects
  Wood Foundation Defects
FAILURES by FOUNDATION MOVEMENT TYPE -recognize & diagnose types of foundation damage by the nature of foundation movement
  BULGED vs. LEANING FOUNDATIONS - distinction of foundation bulging from foundation leaning has important implications for stability
  COMBINATIONS OF FOUNDATION MOVEMENT - the real world of foundation cracks and movement: often more than one force is at work
    Bulge & step cracks
    Earthquake Damage to Foundations
    Flood Damage to Foundations
    Foundation Movement During Collapse
    Other Foundation Step cracks
  HORIZONTAL MOVEMENT IN FOUNDATIONS - detection, causes, effects, evaluation of horizontal or lateral foundation movement; hillsides
    Bulging, Leaning & Sliding Wall
    Horizontal Foundation Creep
    Horizontal Movement & step cracks in brick
    Impact Damage to Foundations
    Thermal Expansion Cracking in Brick
  VERTICAL MOVEMENT IN FOUNDATIONS - detection, causes, effects, evaluation of vertical foundation movement, differential settlement
    Diagonal Cracks in Concrete Foundations
    Diagonal Step Cracking in Masonry
    Differential vs. Uniform Settlement Cracks
    Leaning or Tipping Buildings
    Uniform Width vs. Tapered Foundation Cracks
    Vertical Cracks
FLOOD DAMAGE ASSESSMENT, SAFETY & CLEANUP
  FLOOD DAMAGE TO FOUNDATIONS - examples of flood damaged foundations, flood damage case analysis: were these cracks due to flooding?
FOUNDATION DEFECTS OF OMISSION - recognize things that were left out, like footings, reinforcement, soil compaction, during foundation construction
FOUNDATION CRACK EVALUATION- recognize & diagnose types of foundation cracks, movement, damage, by the size, shape, location, pattern of cracks
  DIAGONAL FOUNDATION CRACKS - causes and significance of diagonal foundation cracks, varies by foundation type & material
  HORIZONTAL FOUNDATION CRACKS - causes and significance of horizontal foundation cracks, varies by foundation type & material
  SHRINKAGE vs EXPANSION vs SETTLEMENT - which foundation materials shrink, which expand, & their characteristic crack patterns
  Sinkholes & Building Damage - sinkhole recognition, significance, cause, underlying geology, areas where sinkholes are worst
  VERTICAL FOUNDATION CRACKS - - causes and significance of vertical foundation cracks, varies by foundation type & material
FOUNDATION BULGE or LEAN MEASUREMENTS - procedure for documenting the amount of lean or bulge in a foundation or other building wall
FOUNDATION DAMAGE SEVERITY - rules of thumb for deciding how much foundation movement requires further action
FOUNDATION DAMAGE REPORTS - how to report foundation inspection results and damage
FOUNDATION INSPECTION STANDARDS - definition of scope of what a foundation inspector
FOUNDATION MOVEMENT ACTIVE vs. STATIC - determine if foundation movement was a one-time event or an ongoing problem
FOUNDATION REPAIR METHODS - catalog of methods used to repair damaged foundations and masonry building walls
  Bulged foundation Repairs
  Crack Repair Methods
  Horizontal Movement Repairs
  Shrinkage Crack Repairs
  Vertical Movement Repairs
SITE FACTORS AFFECTING FOUNDATIONS - drainage, rock, soil compaction, slope or grading, bedrock, sloping bedrock, proximity to roads
SLAB CRACK EVALUATION - recognize and diagnose different types of slab or concrete floor cracks and movement
  Control Joint Cracks in Concrete - what are control joints, why they are needed, what happens when they're omitted; are they structural?
  Freezing & Water Damage - recognize frost and water damage to concrete slabs, distinguish from other crack types
  Frost Heave/Expansive Soil Cracks in Slabs - distinguish between frost damage and expansive clay soil damage to slabs
  Seal Cracks by Polyurethane Foam Injection - stop basement or crawl space leakage
  Seal Cracks in Concrete, How To - products and methods used to seal or repair cracks in poured concrete walls, foundations, floors, & slabs.
  Settlement Cracks in Slabs - recognize slab settlement, assess risk, assess potential impact on structure
  Settlement Cracks vs. Frost Heaves - how to tell the difference between frost heaves and foundation settlement; does it matter?
  Settlement Cracks vs. Shrinkage Cracks - critical identification of shrinkage cracks (non-structural) compared with foundation movement
  Shrinkage Cracks in Slabs - causes, prevention, assessment of concrete slab shrinkage cracks
  Shrinkage Cracks Along Foundation Walls - why do we see a gap between a poured concrete slab and its abutting foundation wall?
  Standards for Repair of Cracks in Floors - when does a floor or slab crack need to be repaired? why?
WATER ENTRY in BUILDINGS
  SUMP PUMPS GUIDE - how a sump pump can avoid foundation damage and reduce building water entry
ADDITIONAL READING

• Thanks to Alan Carson and Bob Dunlop, Carson Dunlop, Associates, Toronto, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education, publications, report writing materials, 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
• 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
• Aaron Kuertz aaronk@appliedtechnologies.com, with Applied Technologies regarding polyurethane foam sealant as other foundation crack repair product - 05/30/2007
• 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. *
• *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)

Please see FOUNDATION INSPECTION STANDARDS

Technical Content Reviewers for Foundation Crack and Movement Damage Evaluation, Diagnosis, & Reporting

• Daniel Friedman - principal author/editor of the InspectAPedia^® Website
• 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
• 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
• Aaron Kuertz aaronk@appliedtechnologies.com, with Applied Technologies regarding polyurethane foam sealant as other foundation crack repair product - 05/30/2007
• Bob Peterson, Magnum Piering - 800-771-7437 - FL*
• 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
• 03/24/2009 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.
• 2/6/99 editing updates, soliciting additional reviews
• 2/3/99 Converted working text file to MSWord97 .doc and .htm files for easier review on Internet
• 6/26/95 text updates per comments from Al Carson, Terry Carson, Mark Cramer 6/16/95 text updates for Calgary July 1995
• cc's sent to reviewers
• 3/28/95 uploaded to ASHI's Internet site - asfoun01.txt
• 11/19/93 Ed Seaquist - telecon 11/19/93, likes, will write up one of our sections for my/our target of series of journal articles or a book.
• © Dan Friedman 1999, original 1992 All Rights Reserved -- foundation.htm

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
• inspect-ny.com - The Free Home Inspection & Construction Diagnosis Public Information Website

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