How to Evaluate the Significance of Foundation Movement or Damage

How to Evaluate the Significance or Amount of Foundation Movement when a foundation is leaning, bulging, bowing, or settling
- Extent of foundation damage
- Photographs of foundation crack patterns
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How to Evaluate the Significance or Amount of Foundation Movement when a foundation is leaning, bulging, bowing, or settling.This document 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.

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.

FOUNDATION DAMAGE SEVERITY - How to Evaluate the Significance or Amount of Foundation Movement when a foundation is leaning, bulging, bowing, or settling

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.

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.

Some simple "rule of thumb" for evaluating the seriousness of foundation damage

Amount, type, & direction of foundation movement

Bulging brick - if broken bond courses, very serious/dangerous (1/3 "rule"-A. Carson; author opinion: this needs clarification. 1/3 of wall thickness looks like much too much movement to allow--DF.)
Bulging masonry block - risk of collapseVertical & horizontal dislocation - depends on amount

The importance of the amount of foundation movement varies

Wall height, type of construction, materials
Implications for building: structure-pulled framing apart?
Site factors which increase risk: earth loading, water

Climate, seismic, & other local foundation structural requirements

Earthquake design requirements for reinforcement

Cold-climate design requirements for reinforcement, drainage, frost protection

Storm/High-wind (and earthquake) design requirements for connections to framing (not considered here)

Other Expert Views regarding Evaluating Foundation Crack Size or Extent of Movement
StructAPedia ^®

British Royal Institute of Chartered Surveyors, RICS - Degree of Damage - per W.H. Ransom (RICS)

Very slight/slight single, isolated cracks - Fine cracks, <5mm (.3") wide, slight sticking windows/doors
Moderate - 5-15mm (.2"-.6") wide, point up brick, some local replacement, doors/windows stick, pipes may break, not weather tight
Severe/very severe - > 15mm (.6") to > 25mm (1"), walls likely to lean, bulge, may require shoring; beams may lose bearing; windows distort, glass may break, pipes probably break. External repairs needed, partial or complete rebuild.
Multiple small cracks, leaning, shifting can be serious too.

FOUNDATION DAMAGE SEVERITY TERMS - How to Characterize the Severity of Foundation Damage
StructAPedia ^®

Based on multiple national ASHI seminar polls conducted by the author - American Society of Home Inspectors (ASHI)

Minor, single, isolated, cosmetic, marketing concerns

Cracks, hairline to 1/16" horizontal
Cracks, hairline to 1/8" vertical and step; [1/4" ? per Alk - note that this is an unsubstantiated opinion]]
Cracks in slabs, hairline to 1/8", not extending into foundation

Modest foundation damage, monitoring appropriate

Horizontal bulge < 1.5", no signs of other significant damage
Leaning wall < 1/3 of wall thickness, from wall base (In author's opinion 1/3 is way too much movement to tolerate; a conventional thickness masonry block wall that leans in one inch over an 8' ht. (or maybe 1.5" per some surveys) might be monitored depending on other site conditions, history, etc. Walls buckled in or leaning more than 1" (or 1.5" in some jurisdictions) should be professionally evaluated further and may require near-term or even immediate repair; Walls buckled in or leaning an inch or less should be monitored.
If the cracks are old, with no sign of continuing/recurrent movement - the inspector is more likely to accept monitoring rather than requiring repair.
Cracks described by "wavy mortar" which were caused by damage during backfill while mortar was still "green" or soft (un-cured) and which are not accompanied by other signs of ongoing or additional movement, can be attributed to a single-event and may not require repair (depending on total amount of wall dislocation).

Significant, expert foundation assessment needed. Foundation repair may be needed

>1.5" horizontal bulge/lean or lateral dislocation >1/4".
Signs of active, recent, recurrent movement (may be seasonal or ongoing)
Sudden appearance of cracks, particularly in areas known to have sink-holes (e.g. some areas of the U.S. such as in Florida.) requires immediate assessment.
Signs of repeated repairs to foundation or interior
Cracks 1/4" [ 3/8" per Alk] & larger
Investigate any finding of which the inspector is uncertain or inexperienced.

WARNING: Don't make conclusions just based on crack size and location. The inspector must consider other site factors conditions, history, materials, external forces, etc. Sudden catastrophes CAN occur, especially where site drainage or other conditions risk undermining or sudden forces on the foundation.

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Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

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. * 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, 25th Ed., 2012, 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. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

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Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for certain articles found at this website. All rights and contents to those materials are ©Journal of Light Construction and may not be reproduced in any form.
Appliances and Home Electronics, - energy savings, U.S. Department of Energy
Avongard foundation crack progress chart for structural crack monitoring
Basement Moisture Control, U.S. Department of Energy
Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF] ISBN-10: 0471331724 ISBN-13: 978-0471331728
Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008) ISBN-10: 1405161035 ISBN-13: 978-1405161039
The Circular Staircase, Mary Roberts Rinehart
Construction Drawings and Details, Rosemary Kilmer
Crawl Space Moisture Control, U.S. Department of Energy
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.
Building Failures, Diagnosis & Avoidance, 2d Ed., W.H. Ransom, E.& F. Spon, New York, 1987 ISBN 0-419-14270-3
Domestic Building Surveys, Andrew R. Williams, Kindle book, Amazon.com
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.
Guide to Domestic Building Surveys, Jack Bower, Butterworth Architecture, London, 1988, ISBN 0-408-50000 X
"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
Energy Recover Ventilation Systems for Buildings, U.S. Department of Energy
Energy Savings Methods: Whole House Systems Approach, U.S. Department of Energy
Historic Preservation Technology: A Primer, Robert A. Young, Wiley (March 21, 2008) ISBN-10: 0471788368 ISBN-13: 978-0471788362
Log Homes: Minimizing Air Leakage in Log Homes, U.S. Department of Energy
Log Homes: Controlling Moisture in Log Homes, U.S. Department of Energy
Log Homes: Log Home Design, U.S. Department of Energy
Moisture Control in Buildings, U.S. Department of Energy
Moisture Control in Walls, U.S. Department of Energy
Quality Standards for the Professional Remodeling Industry, National Association of Home Builders Remodelers Council, NAHB Research Foundation, 1987.
Quality Standards for the Professional Remodeler, N.U. Ahmed, # Home Builder Pr (February 1991), ISBN-10: 0867183594, ISBN-13: 978-0867183597
Natural Ventilation for Buildings, U.S. Department of Energy
R-Value of Wood, U.S. Department of Energy
Spot Ventilation for houses, U.S. Department of Energy
Slab on Grade Foundation Moisture and Air Leakage, U.S. Department of Energy
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.
"Vapor Barriers or Vapor Diffusion Retarders", U.S. DOE: how vapor barriers work, types of vapor diffusion barriers, installing vapor barrier
Ventilation for energy efficient buildings, Purpose, Strategies, etc.,


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