Methods for Monitoring Foundations for Evidence of Ongoing or Episodic Movement
How to report the condition of a building foundation
How to describe foundation damage and recommend action
Methods for monitoring & reporting on foundation cracks & movement - foundation crack monitors
InspectAPedia offers impartial, unbiased advice without conflicts of interest.
We will block advertisements which we discover or readers inform us are associated with bad business practices,
false-advertising, or junk science. Our contact info is at
InspectAPedia.com/Contact.htm.
This document describes how foundation or slab cracks can be monitored for evidence of movement and what general advice makes sense for building owners or buyers where foundation damage
is found and/or where further foundation inspection, testing, diagnosis, or repair appear warranted based on a general field inspection.
We include discussion of methods used to perform ongoing monitoring of building foundations for cracking and movement.
Methods for Monitoring Foundations for Evidence of Ongoing or Episodic Movement
Building foundations may be moving, either continuously or episodically. Most movement is episodic, that is, the movement is not a simple and continuous creep but rather foundation movement or cracking occurs in fits and starts. Our sketch (left) shows a bulged masonry block foundation wall that has bowed in two inches at its innermost point.)
Usually foundation movement and further cracking occurs in response to occurrences of what has caused the cracking in the first place.
Examples of Causes of Ongoing Foundation Damage/Movement
Continuous vehicle traffic too close to the foundation (weight) or even in a nearby roadway (vibration)
Continuous blasting and nearby site work
Continuous overloading or point loading on the foundation due to construction or building design
On occasion a foundation cracked or damaged by an event (drove a heavy vehicle too close to the masonry block foundation wall) may later move, crack or bend, buckle, lean, bulge, etc. in response to other site conditions that it was previously able to resist before it was weakened by the original damage (frost, water, other vehicles).
Examples of Episodic or Discontinuous Causes of Foundation Damage/Movement
Seasonal area flooding of surface water or subsurface groundwater
Seasonal freezing weather - frost heaving and frost lensing
List of Simple Methods to Monitor a Masonry Foundation for Evidence of New or Ongoing Movement
Crack Pins to monitor masonry structure movement: a metal pin is secured to the masonry surface on either side of the crack. Periodic measurements are made of the distance between the two points of the pins.
Crack monitor slide devices: such as a glass slide, a more complex set of moving glass slides that include fine markings can be epoxied (or mechanically fastened) across a building foundation crack.
Masonry crack monitoring devices provide accurate indication of any additional movement in the foundation wall. Beware: small amounts of foundation movement occur in masonry materials as a normal effect of temperature and moisture changes and may be typicallyi a millimeter or so. Don't mistake these causes for ongoing building movement. (Photo above courtesy of Avongard.)
The Avongard crack-monitoring device, a $16.00 U.S. device measuring 1.25" x 5.75", is an example of this product. "The Avongard Crack Monitor consists of two overlapping acrylic plates. One plate is white with a black millimeter grid, while the other is transparent with red cross hairs centered over the grid.
Once the Crack Monitor is in position across a crack, the cross hairs shift vertically or horizontally on the grid if movement occurs,so that anyone can easily see and track crack movement." (Photo at left of a crack monitor in place is courtesy of Carson Dunlop Associates.)
The Avongard crack monitor can identify masonry wall movements down to 0.5mm and can handle total movement of 30.75" in crack width and 0.375" upwards movement (one side of the surface lifting or protruding past the other, such as on a concrete floor).
For longer term monitoring of a cracked masonry wall or floor we like this device. The monitor can also be used to measure movements in foundation corners by incorporating an angle bracket. Avongard provides a movement progress chart that permits logging of observations over time.
Masonry Crack Fillers: if a horizontal, vertical, or diagonal masonry crack is filled with hard masonry patching compound, any substantial future movement is likely to show up as a new crack in the patched area (or nearby). Beware: some masonry products shrink when they dry and cure - don't mistake a patch shrinkage crack for building movement. But if a foundation crack is leaking you'll want to seal it, not just monitor it.
Masonry Crack Caulks: filling a foundation crack with a masonry caulk is a quick, inexpensive, and effective way to seal the crack; some caulks, such as pourable sealant used to close floor cracks during radon mitigation work, are easy and effective to use. Beware: flexible materials won't show small amounts of future building movement.
Measure and Document Foundation Movement: masonry foundation cracks alone may not be the only nor even the most critical evidence of foundation movement. If a foundation wall is leaning, bending, or bowing, that stress may have resulted in several small width cracks that do not adequately describe the total amount of foundation movement.
A written and photo inventory of foundation cracks, simple measurement of foundation crack length and width as well as documenting their location, may be combined with simple measurements of the total lean or bulge in a foundation wall. (Photo courtesy Carson Dunlop). See FOUNDATION BULGE or LEAN MEASUREMENTS for details.
A foundation inspection & diagnostic report: a thoughtful inspection of the building and site as well as an inventory of existing cracks permits a diagnosis of the causes of foundation damage as well as its extent. If there is evidence of significant foundation movement, we recommend that you take this more costly step. See FOUNDATION CRACK EVALUATION for guidance.
Other foundation movement monitoring devices are used by professional engineers, including load cells or pressure cells, extensometers used with a borehole and tape, tilt meters that measure angular change or lean, strain meters, beam sensors, and soil movement sensors. Companies such as Slope Indicator sell these and other sensing and measuring devices.
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.
"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
Avongard crack monitors, Santa Monica, CA 90406, 800-244-7241 can be reached by email to info@avongard.com
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.
Forensic Geotechnical and Foundation Engineering, Robert W. Day, McGraw-Hill Professional, 1998, ISBN 0070164444, 9780070164444, 460 pp. Mr. Day discusses the Avongard crack monitors and other foundation monitoring methods - p. 48-49.
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
Journal of Light Construction articles are available on CD ROM from the Journal of Light Construction, www.bginet.com, 802-434-4747
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.
Mobile View
