Foundation movement: how to detect & diagnose active movement in a building foundation InspectAPedia® -
Foundation movement: how to detect & diagnose active movement or movement cracks in a building foundation
Types of foundation damage
Extent of foundation damage
Photographs of foundation movement crack patterns
Questions & answers on how to determine if foundtation movement or damage is active and ongoing
Determine active vs. old building foundation or structural movement: This article explains Foundation movement: how to detect & diagnose active movement or movement cracks in a building foundation.
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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.
MOVEMENT ACTIVE/STATIC - Foundation Movement: Determining Active or Dynamic (ongoing movement) vs. Static (no ongoing movement)
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.
How to evaluate the extent and importance of building foundation movement
How to determine the age of foundation cracks
Look for clues indicating old vs. new cracks and active vs. static cracks.
For example, evidence of repeated repairs (patched, re-cracked, re-patched) is clear indication of recurrent movement.
Evidence that a crack occurred at time of construction (in an older house, such as wavy mortar which "bent" in the mortar
joints as a wall was loaded) is clear indication of an old condition which may or may not be accompanied by other evidence of later movement.
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. 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 in building foundations 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.
Questions & Answers regarding this article
Questions & answers on how to determine if foundtation movement or damage is active and ongoing.
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Additional technical contributors & reference sources for this article are listed below.
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"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. * Mr. Wickersheimer's engineering consulting service can be contacted at HDC Wickersheimer Engineering Services. (3/2010)
*These reviewers have not returned comment 6/95
ADDITIONAL READING about Foundation Failure Diagnosis & Repair
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
InspectAPedia.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
Authority
Opinions herein are the responsibility of the author. Most of this material has been subject to ongoing peer review but is without any professional engineering analysis. Home inspections may include the discovery of defects involving life, safety, and significant costs. Home inspectors who are not both qualified and certain of the authoritative basis of their conclusions should obtain their own expert advice from qualified experts.
This work is also based on the author's construction & inspection experience, training, research, and survey of material from ASHI, and from N. Becker, R. Burgess, J. Bower, D. Breyer, A. Carson, J. Cox, A. Daniel, M. Lennon, R. Peterson, J. Prendergast, W. Ransom, D. Rathburn, E. Rawlins, E. Seaquist, and D. Wickersheimer. Some useful citations are at the end of this paper.
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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