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The Foundation Crack Bible - Foundation Cracks, Leans, Bulges, Settlement: Inspecting Foundations for Structural Defects - Detection, Diagnosis, Cause, Repair StructAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com 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

The photo above 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 we're in process of adding these photographs to this website. Pending completion of that work, contact the author if assistance is required.

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.

FOUNDATION DIAGNOSIS Chapter Index

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Technical Reviewers

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - principal author
• "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.

MOVEMENT ACTIVE/STATIC - Foundation Movement: Determining Active or Dynamic (ongoing movement) vs. Static (no ongoing movement)

How to evaluate the extent and importance of building foundation movement

Please see FOUNDATION MOVEMENT ACTIVE vs. STATIC for our complete discussion of this topic.

How to determine the age of foundation cracks

How to look for evidence of horizontal foundation movement or wall displacement

Horizontal wall movement: Look for evidence of horizontal wall displacement, lateral displacement such as frost push of a masonry block wall. The bottom block course, held in place by the floor slab, may be in the original location while the first course above or higher courses may have been pushed horizontally inwards.

How to evaluate foundation wall leaning, tipping, or bulging

Wall tipping or leaning: Look for evidence of wall tipping or leaning - the entire wall has remained flat but leans inwards at the top.

Wall bulging: Look for evidence of wall bulging, locate the center of the most bulged-in section and note its height above the bottom of the wall and its relative position to the top of grade outside.

How to measure the amount of lean or bulge in a foundation wall

Measuring foundation wall tip, lean, or bulge: is simple: drop a plumb line near the most-bulged area (usually the center) of the wall, perhaps fastening it to a nail in a floor joist overhead, about 4" in from the wall. Measure from the string in to the wall at various heights up the wall. You'll be able to easily pinpoint the height of the most bulge or lean. This is not engineering. It's simple a simple mason's method to measure a wall or chimney during construction to keep it plumb. [You may need to hire the services of a licensed professional engineer, one who is experienced with foundation troubleshooting and repair, especially if there is need to design a special building repair method or if there is apparent risk of possible building instability or collapse.] Wall most-bulged in near the outdoor ground surface (commonly occurs in the upper 1/2 of the wall), perhaps at a depth equal to the frost line in climates where freezing occurs or in the top 1/3 of the wall if we suspect water or frost loading on the wall, or possibly vehicle traffic driving too close to the wall. Wall most-bulged in at its center height - the center of the overall height of the wall (common) - we suspect vehicle traffic or possibly water/earth loading Wall most-bulged in near its bottom (unusual) - we suspect earth loading or wet earth loading. Details: a plumb line, that is a string suspended by a weight, gives a perfectly vertical line from which to measure back to the wall surface. We don't care about the absolute value of the various measurements, we care about the difference between these measurements. Usually the very bottom of a building wall will not have moved inwards, particularly if a concrete floor has been poured against the foundation. The entire building floor slab is acting as an "anchor" to hold the bottom of the foundation wall in place. So we take the distance between the foundation wall and the string at the bottom of the wall as our "home base" or point of assumed "zero movement". We compare this measured value with the other measurements between the wall and the string. If the foundation wall or any part of it higher than the floor has moved, tipped, or bulged inwards, those measurements from wall-to-string will be less than the distance, wall-to-string measured just above the floor level. That's because the wall has moved inwards, towards the string. An example of measuring the amount of foundation wall bulge inwards We "eyeball" the "bulged" foundation wall and guess at the point at which it is bulged inwards the most - perhaps close to the center of the length of the wall (right-to-left dimension) We hang our string or plumb line from the nearest floor joist, keeping the string a few inches away from the foundation wall We measure 4.00 inches between the foundation wall surface to our vertical plumb-line string at 1" above the concrete floor - this is our "zero point" or "home base" measurement We measure 2.00 inches from the same foundation wall surface to our vertical string at a height of 5' from the floor We measure 3.25 inches from the same foundation wall surface to our vertical string at the very top of the wall just under the sill plate. We check that we've measured at the area of greatest inward bulge in the wall by moving our plumb line to our left, then to our right on either side of the ceiling joist we used to hang the string for our first measurement. If the distances we measure, wall to string, are greater than the distances we measured at our first trial, then that one is the point of greatest inwards foundation wall bulge. Finally we do the math: subtract our "higher on wall" and "closer to string" measurements from our "at the floor" and "farthest from string" measurement. Completing our Calculations of the Amount of Foundation Movement We See These Results Foundation Wall Bulge-in at floor = 0 inches Foundation Wall Bulge-in at 5'up from floor = 4" - 2" = 2" of inwards bulge Foundation Wall Bulge-in at the top of the wall = 4" - 3.25" = .75" of inwards lean How to distinguish between a "bulged" foundation wall and a "leaning" foundation wall, and why we care Characteristics of a leaning foundation wall 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). 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. Even a concrete wall which is bulged is going 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. Other cases of leaning or moved foundation walls may produce different measurements Horizontal foundation wall movement, creep, non-leaning lateral shift On less frequent occasions we've found that an entire masonry block wall (or portions of it) were pushed horizontally inwards by some outside force, without causing the wall to lean or bulge. In a pure example of such a case, all of the differential movement measured (wall to string) between the wall bottom point (held in place by the floor slab) and the inwards-pushed wall section, will be a horizontal movement of that portion of the wall, and if it's masonry block, you'll see that the inwards-moved blocks are "hanging over" or projecting past the surface of the masonry blocks that did not move. Combinations of foundation wall movement You may encounter a foundation wall which has moved inwards in a combination of forms, both bulging at its most-pushed-in point (with horizontal cracks in the foundation wall) and the wall may have also been pushed inwards sliding some of the masonry blocks inwards past others which have remained in place. In this case you'll see both that some masonry wall blocks will overhang or protrude past others in the wall (usually upper inwards pushed blocks hang over lower more stable blocks closer to the floor), and there may be bulging and cracking at another elevation of the wall. 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. Other step cracks will of course also occur in building masonry block foundation 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. Other vertical cracks can occur in a masonry block or concrete or brick or stone foundation wall without leaning or bulging if the wall is moving due to footing settlement or frost.

Questions about active (dynamic) foundation movement

When we find visual or measured evidence of cracking and movement in a masonry foundation wall of any type, there are some diagnostic questions we can ask that help assess the cause of the problem and the urgency of repair actions:

• Constant rate of foundation movement: Does the evidence suggest that cracking and foundation movement are occurring at a constant rate?
• Accelerating rate of foundation movement: Is there evidence that the wall movement is accelerating?
• Decelerating rate of foundation movement: Is there evidence that the wall movement is decelerating?
• Seasonal rate of foundation movement: Is there evidence that the wall movement is seasonal or intermittent? One of our associates has a masonry block garage foundation wall which heaves and moves up and down every spring.
• Site-Work-Related of foundation movement: Is there evidence that the wall movement is related to ongoing site work?

NOTE: without historical data these causes can be difficult to confirm without monitoring. Active movement requires at least monitoring; present or future repair steps likely.

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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's 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.

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Articles Describing Typical Foundation Repair Methods

The articles listed here describe repair methods for foundation cracking, moving, creeping, leaning, bulging, bowing, or settlement:

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FOUNDATION REPAIR METHODS
  Crack Repair Methods
  Shrinkage Crack Repairs
  Vertical Movement Repairs
  Bulged foundation Repairs
  Horizontal Movement Repairs

ADDITIONAL READING about Foundation Failure Diagnosis & Repair

Foundation Inspection Standards - ASHI Standards of Practice (American Society of Home Inspectors)

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FOUNDATION INSPECTION STANDARDS

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

• Daniel Friedman - ASHI (1986-2006) - author of this website and article, 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, 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*
• *These reviewers have not returned comment 6/95

Technical Edits, Changes, Amendments to This Document

• 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 my sections for my/our target of series of journal articles or a book.
• © Dan Friedman 1999, original 1992 All Rights Reserved -- foundation.htm

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More expert information on this topic

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

NOTE: Journal of Light Construction articles are available on CD ROM from the Journal of Light Construction, www.bginet.com, 802-434-4747

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